It's hard to miss the fact that Commerce players, especially Asian ones, are delighted to check raise turn. Looks like they are truly addicted to this kind of fun. To me, this hobby of their become quite a money bleeding factor over last month and I am trying to understand if this is my runbad or do I have some true leak in my strategy and adjustments are needed. So I will start to post some hands.... In general, it is clear to me that they lose value in spots where I will check behind the turn with my medium value range. OTOH, when I have to bet with my top value range, especially on wet boards, and face a check raise - I still didn't wrap my mind around their ranges to figure where to find a fold. Probably I need to start folding stronger, TP+ type hands because they always seem to have it, or, again, is this result oriented run-bad impression?
So if anyone can provide some generic thoughts on potential adjustments etc' I will appreciate it.

Hand:
Villain (SB) is seemingly passive, ~40 y.o. Asian. I didn't play with him enough (just a few orbits), he makes all classic mistakes of cold calling, limping etc' and doesn't seem to be crazy, but again, don't know yet. BB is another fish.
Hero opens AT in CO, blinds call
Flop AK4 hero c-bets, SB calls, BB folds
Turn 9 SB check raises, hero calls
River 6 SB quickly bets, hero calls ?

The river changes nothing, IMO, unless you're putting your villain on exactly a spade flush draw (or exactly suited connectors which also picked up a straight draw on the turn in hands where the board makes this a possibility, too; obv., this is not the case in your OP). I think your first question to yourself in hands like this has to be: "Why is this villain check raising me in this spot?" Then, simply assign a general hand range to your particular villain, and ask then yourself: "If I am calling villain's c/r on the turn, am I calling down the river no matter what card comes?" If the answer to this question is "no," then I assume that means you're putting your villain on a very specific hand range, which can be dangerous. It can be quite detrimental to start folding too much on the river after calling the c/r on the turn for two reasons: 1. the pot is laying you a huge price, most often, to call, so any mistakes in your reads become super costly; and 2. good players perceive a super exploitable leak in your game if you're calling c/r's on the turn and then folding to river bets, as this is generally a very weak line.

Bottom line: it used to be that anytime we got c/r'd, we knew we were up against a monster. This isn't true anymore in most 20 games and higher because good players--as well as action junkies--have learned to exploit the overly-aggressive play of people who rarely (if ever) check or call (IMO, too many 2 + 2'ers are allergic to calling at times when it is absolutely correct--especially if we've procured the proper table image prior to the call). So in 2012 when we get c/r'd, the considerations have changed, and we must ask ourselves why we've been c/r'd (what is our image? is villain capable of the c/r bluff? is villain capable of getting thin value by c/r'ing because villain knows that's it's mad important to get in that one extra BB? is this an "old skool" c/r, and villain has the monster and perceives us as a calling station, etc., etc.), and also make a decision for what our line will be on the river before we put in anymore action on the turn. And obv., if you think Commerce maniacs are c/r'ing you too often with draws or for thin value, you MUST 3 bet them after getting c/r'd to slow them down and to let them know you're not a bich. At least, that's my opinion. With more thinking players, we can simply call down once or twice to send a clear message that we will not get run over by the c/r...

Finally, I should note as a caveat to my post that I never play in CA, and I know that the games there play very differently from the games on the East Coast and in the South, so to the extent to which I have developed my own strategies in the situation you describe in your OP, I should be clear that those strategies work for me in the games I play in and may be less profitable at Commerce (?!). Your post makes it crystal clear that you are trying to deal with a trend specific to the Commerce, so if I have nothing good to contribute here, sorry to have wasted your time. But the whole c/r thing is, IMO, becoming a more and more prevalent play by both strong players and by maniacs, so I do think your OP presents a good inquiry that is most worthy of discussion...

GL.

Without a range, you can't know what to do here.

With a range, you can stove it and determine how much equity you have to call down at the pot odds he is giving you.

I absolutely agree... the problem is that seems like for now I am failing to identify this range properly and think that it is weaker / wider than it is in reality. But it is really tough to know as I played a hand yesterday where an Asian guy check raised 3 people on a turn on a super scary board in a huge pot and then check/mucked the river w/o showing and I won with A hi because I happened to have an FD and had to call.

Pay attention and take note (if not actually taking notes). You need to get a handle on what a turn check-raise means, rangewise, for a given villain. And sometimes that is going to involve paying to see a showdown or two.

Try to make those showdown calls in places where you think you might have a chance of having a good hand. Paying just for information can be expensive. But the information you gain may well compensate for the slight negative EV of a marginally bad call.

From the comfort of my east coast chair, I'm having a hard time seeing how this is a good example of a hand that gives you problems. IMO these players are pretty polarized after taking this line but there's less strong stuff because of the preflop cold call. I'm going to have to learn that this guy can have AK/AQ before I start thinking about folding this river, because otherwise there are too few flushes (As on board) and too many broadway gutshots.

So I made this Stove exercise and looks like we have the right odds to call OTT, assuming he has a lot of flush draws in his range:
Board: As Kd 4h 9s
Dead
Hand 0: 35.953% 29.99% 05.97% 950 189.00 { AcTs }
Hand 1: 64.047% 58.08% 05.97% 1840 189.00 { 99, 44, A9s+, A4s, KsQs, KsJs, KsTs, Ks9s, Ks8s, Ks7s, Ks6s, Ks5s, K4s, Ks3s, Kd2d, Ks2s, QsJs, QsTs, Qs9s, Qs8s, Qs7s, Qs6s, JsTs, Js9s, Js8s, Js7s, Js6s, Ts9s, Ts8s, Ts7s, Ts6s, 9s8s, 9s7s, 9s6s, 8s7s, 8h6h, 8s6s, 7s6s, 7s5s, 6s5s, 6s4s, 5s4s, 4s3s, A9o+, A4o }

But we really have to fold OTR, even getting 9:1 :
Board: As Kd 4h 9s 6s
Dead:

equity win tie pots won pots tied
Hand 0: 06.154% 01.54% 04.62% 1 3.00 { AcTs }
Hand 1: 93.846% 89.23% 04.62% 58 3.00 { 99, 44, A9s+, A4s, KsQs, KsJs, KsTs, Ks9s, Ks8s, Ks7s, Ks6s, Ks5s, K4s, Ks3s, Kd2d, Ks2s, QsJs, QsTs, Qs9s, Qs8s, Qs7s, Qs6s, JsTs, Js9s, Js8s, Js7s, Js6s, Ts9s, Ts8s, Ts7s, Ts6s, 9s8s, 9s7s, 9s6s, 8s7s, 8h6h, 8s6s, 7s6s, 7s5s, 6s5s, 6s4s, 5s4s, 4s3s, A9o+, A4o }

Yeah is he really A9+ cc pre? Im doubtful about that from the top down. But evidence is evidence.

I kinda disagree. If we don't know what villain's range is, the best solution I think is to just resort to a GTO type approach. Fold our worse value hands and call down with the rest.

If we feel villain's range is likely stronger than GTO, but we're not sure, then we fold a few more of our worst hands and call down with the rest.

I would say as long as your not making drastic changes to how you would play hands based on potentially bad/wrong initial reads, you won't be making many mistakes, and when you do, they will be small mistakes.

I am 90% sure he doesn't 3-bet AJ and AQ, doubtful about AK (and he didn't have any of these hands here, so I am not result oriented)

Well, I agree that this is what you should do against a total unknown.

That really wasn't what I was saying though. Essentially, playing GTO here can be quite "wrong" in the sense of paying off way too many hands against players who always, as OP said, "have it" when they wait for turns. And we've all played against players like that. You're giving up substantial amounts of money not making exploitative folds against players who wait for the turn with monsters and never with weaker value hands or bluffs.

So to make the proper exploitative folds, you need to come up with a decently accurate range and stove it (as OP attempted to do after I suggested it). Then you don't really need to worry about GTO; you can just call down when Stove tells you to.

But if you have no information from which to make an accurate range, then yes, you can't exploit at all, and GTO is the way to go.

In my kneck of the woods its (usually) 2p or very strong draws. So what your stove.calculated is pretty much how I'd play the hand.

So you're telling me that you saw a dude CR ott and cf when the draw came in? Odd. Not the same Guy though. If it was it'd be a pretty easy fold otr ldo.

I'd say really take note of the guys who are doing this and check back some turns - make a "value " check every now and then Haha. That'll blow some air out of their tires!