This hand happened at a 1-2 table, but it was playing more like a 2-5 game with most pots $100+ and multiple players routinely calling pre-flop raises of $10-20.

Villian is a maniac. He had busted out twice and re-bought in the space of an hour. All the other players were hoping he would come back, and he did. He played 80% of all hands, raising pre-flop 50-60% of the time when limped or folded to him, but never three-betting. Once in a hand, he c-bet 100% of the time and routinely called bets with air -- waiting for opportunities to shove or push in pot-plus bets if no other action happened in front of him on any street. He had caught a couple of miracle hands and amassed a big stack, including a huge pot he won playing 7-2 when he called a $100 flop bet and then a $100 turn bet on a king-high board with two hearts. After the aggressor/bettor checked the river to him, he shoved all-in for his last $150 -- and won because the other guy had missed his flush draw. So, that's the kind of player we're up against.

Hero is UTG with a $4 straddle in front of him. Villian on Hero's immediate left, so mosly out of position against Villain.

Hero has K9 and limps in by calling the $4 straddle. Villain makes it $17, which was typical, and gets 4 callers back around to Hero, who calls. Villain's range here is just about any two cards. Hero has about $400 behind.

Flop is AQ3

Hero checks. Villian (surprise!) checks. Checks around. 5 players Pot ~$85

Turn is K

Hero leads out for $30. (Nobody had bet the flop despite two clubs on board, so Hero figures that nobody has an Ace.)

Comments on lead-out and bet size?

Villain raises to $60. All other player fold. Hero calls additional $40

Pot now $205

River is 9

Hero checks

Villain shoves all-in. Villain has hero covered.

So -- call or fold?

Lots of issues here, IMO.

If he's never 3betting preflop, raise instead of limping.
If you're going to bet turn, bet much bigger. AP, fold turn because you know he's firing any river and anything besides a king sucks for you. Also $30 + $40 != $60
Can't tell you river because you didn't give us stack sizes.

He took the line that tons of maniac-idiots take when they actually hit a hand, and you're behind a LOT here. As long as you have more than $100 in your stack you should fold.

Opening k9o utg is creative advice.

Fold pre

Why is Hero calling this hand preflop? Given the description of the Villain, this is almost like doubling down on 19 vs a dealer 6 in Blackjack.

You're right -- meant to say that if he's going to play it he should raise.

Fold pre

Check the turn. Your hand has showdown value but your are pretty much asking for the maniac to raise your small bet and blow you off your hand. His min-raise actually screams strength and I would be reluctant to put another dime in the pot. You know once he raises here he is going to bomb all river cards so are you prepared to call it off with 2nd pair? if not, you should fold turn otherwise you are lighting money on fire.

Maniac who has bet every time he's had a chance suddenly checks. This doesn't raise any alarms for you?

First of all, fold preflop. Your hand has terrible playability as you've come to realize in this hand. When up against a maniac you can expand your range a bit, but only if you're frequently heads up with him, but I don't think it's advisable to widen it to K9, especially when you know you're going multi-way.

Second, when someone suddenly does the opposite of what they usually do (like checking instead of c-betting) that should cause us to question what is suddenly different.

Third his raise on the turn certainly looks like he wants you to call.

Now onto the river: He shoves (and I'm assuming that he has you covered, if my math is correct you have about $340 left) for about $340 into a pot that has $205 in it. This should be a polarizing bet, but doesn't necessarily have to be vs a complete maniac.

You have a bluff catching hand so anything we put in his value range has you beat. AQ, AK, AA, QQ, JT, two random clubs.

The bluffing hands are harder to come by. For one thing, you hold the key card the king of clubs. You know where the nuts are so that means he can't be bluffing with it and he can't have it. A lot of his bluffs should contain this card.

So what bluffing hands are we left with? QJ (probably with the J of clubs) JJ, TT, some combination of random air hands.

Even against a maniac I think it should be clear we are just beat way too often here to make a profitable call. We're getting a terrible price to call and we beat basically nothing. Easy fold.

Fold

wtf, this whole hand is a travesty. Why the hell are you limping K9o utg? What is your goal here, to hope you get it heads up out of position with a maniac so you can maybe hit a pair and call it off? You realize if nobody raises you are at minimum seeing likely 3 if not 4 ways to the flop when the BB completes and the straddle checks. So now what, you're playing a multiway pot with king rag, brilliant.

On top of that, someone does raise. Sure it's the maniac, but 3 ****ing people called before you. Maybe you have his "any two cards" range crushed right now, but how are you going to navigate this hand with multiple other players in the pot? Just pray that you hit a pair, maniac bets at it, and they all fold? This is a horrible plan.

So you hit top pair in the worst possible way imaginable, dominated with no kicker, facing an ace, and out of position, but whatev's right? Nobody bets and now you go for value or something on the turn? Like, when you bet that turn what are you hoping for? That somebody with a worse king calls and you avoid a chop on the river? That a queen calls? That you get value out of a gutshot draw or something? That someone with 77 doesnt believe you and is going to call with 3 overcards to their hand and 4 players still in the pot? If your hand has any value at this point it's purely a bluffcatcher, not a value hand. So just check, hope the maniac bets and you can be a hero and call him with your K9o. But thats just the turn, lets look at the river;

It is true the proper strategy vs a maniac is to call them down, often lightly. I think generally speaking 2 pair certainly qualifies. Although I question if this guy is as much a maniac as you think, since you have played the hand so awfully up to this point I have serious doubts about your judgement of others players. What you define as a maniac may be rather normal play in the eyes of someone else. I'd need a few more concrete examples other than him bluffing someone off with 72. So far all I've seen is some guy raised early position, minraised the turn and bet 1.5x pot on river. Fish love to take unorthodox lines with big hands. Basically all you are beating is a complete bluff and there is a lot out there he should be scared of, i mean what exactly does he think you're folding when he jams? You look like you have top pair, does he expect you to fold an ace?

So now that you've basically sucked out as good as you can given the circumstances, if he's a maniac sure I go ahead and call it off. But generally speaking this hand is a fold preflop, on the flop, and on the turn at any opportunity. Either move to his left (despite common advice to have relative position, I'd still rather be last to act postflop) or save your antics for when you're near the button and can raise yourself.

Tons and tons of issues. I don't even want to adventure going in details.
Calling the extra $2 for straddle is a mistake that can open lots of trouble. Calling a preflop raise is even a bigger mistake. Are you looking to flop a King?, a 9 or maybe a K9x? or who knows: a K99/KK9? lol..lol..looooool - I mean.., who is still playing K9 nowadays? , Are we not above that level yet?

This thread gives me so much hope in the profitability of live poker