The limpers are very loose, bad players.
189 hands on BB, he is 24/27/Afq 53, WtSD 50. Street by street Afq is 67/52/31. He's played over-aggressively with TPWK.

[converted_hand][hand_history]Poker Stars, $1/$2 Limit Hold'em Cash, 6 Players
Poker Tools Powered By Holdem Manager - The Ultimate Poker Software Suite. View Hand #12928052

Preflop: Hero is SB with Q 3
UTG folds, MP calls, CO folds, BTN calls, Hero completes, BB checks

Flop: (4 SB) 3 9 8 (4 players)
Hero checks, BB bets, MP calls, BTN folds, Hero calls

Turn: (3.5 BB) A (3 players)
Hero checks, BB bets, MP folds, Hero?

I'm slightly tempted to turn my hand into a semi-bluff on the turn. But from a GTO point of view, it seems that pairs make up too much of his range for him to fold, even really weak pairs like 44-66 (assuming those are in his range). So just c/c turn and make a decision on the river?

So, the read is that he's an over-aggressive showdown monkey. The plan is to exploit this by finding spots to bluff him off a hand?

Your hand range of strong hands is super small and is highly skewed towards draws if you CR the turn on this board. I'm not sure what you're trying to represent here.

*g*

I agree with this. From what you state, it doesn't seem he'll fold. If the FD doesn't hit, you're out 2 bets instead of 1. I would count on him betting the river, so a raise there would be better. If it doesn't, it's an easy fold.

All draws and single pair hands in his range are never folding to a c/r. And since you'll always be seeing the river with him, you're somewhat tied to a kinda gross bluff on the river when you miss (edit: I know you have bottom pair, but I consider that more of a bluff at that point, 'cause nothing worse is ever calling imo).
Also, he'll rarely have something really nice worth 3betting the turn in a spot where you're behind but cannot fold. I just c/c; probably have to call several rivers without improving against an aggro villain. Edit: Though I guess his river aggro isn't much....hmmm.....I still might call what few 100% blank rivers there are.

It is one of those spots where you have a little showdown value until you c/r the turn. Then, you drive out his bluffs and weaker hands that spew-barrel. By narrowing his range, you don't really have SD value. Turning your hand from a weak SD hand into a bluff is fine, vs. a guy who doesn't show down a ton. Also, your draw is such that you can never fold the turn if he spew-rebluffs you. Since you fold to the continuation bluff on the river, you're maximally rewarding his spew. That's the issue with going after a guy who makes silly play in this fashion with this hand -- you actually reward the bad plays he's likely to make. Versus other players, you punish their bad plays taking this same line. Hence, I think you've pulled the wrong club for your lie and distance to the pin.

This was precisely my first thought.

Yeah I agree with everything people have said. For one thing, I don't think his hand range is going to be all that wide considering he bet the flop in a 4-way pot. For that reason (and his low river Afq), assuming I check/call the turn and don't improve, it's questionable if I should c/c the river. This has to be one of the weaker hands in my range and it would be pretty ballsy of him to bet the river with worse.

*g*

I like raising if he's the sort of bad player who'll check to you and give you a free showdown if you miss.

If he's the sort of bad player who'll carry on betting regardless, I prefer calling and folding if you miss.

if you check/raise here you're representing a very narrow hand range. Just weak suited aces with a BDFD and what... AT? We might even discount these hands and say just A6s-A7s, ATo.

I don't see the point actually.