$40 river bet into $30 pot, has to be bluff, no?

[veryblind]

This is live $2/3 $100 buy-in game.

Hero has about $200. villain in SB has about $90.
Folds around to me on BN and I raise to $15 with 99.
SB calls, BB folds
flop: Ad Kh 7d
SB checks, BN checks
turn: As
SB checks, BN checks
river: 3d
SB bets $40

OK, so I'm pretty sure I made a mistake before the river so I deserved to lose this pot. I think check on flop is fine for controlling pot size though bet would be ok too, however I think betting flop turns my hand into a bluff (thoughts?). But I definitely should have bet on the turn.

Now, what can villain have that would make him bet $40 into a $30 pot. Made flush should be scared of full house, no? The overbet is neither a value bet or blocking bet. So what could it be other than a busted suited-connector?

The only other play I was scared of that he had a monster, (e.g. AK) and was trying to induce a call with a suspiciuos overbet. But this a rare play, even in live games where I think it happens more often.

If this hand requires reads, then I can provide some more info.

Also, if it makes a difference, this was villain's last hand before table change. And as I picked up my hand to muck, he whispers to me he hit the 3 on the river with pocket 33's. In retrospect, I should have asked him what suits he had to see if I can catch his eyes glimpsing back at at the board. But anyway, I don't to make this discusson about tells.

Thanks in advance

[SABR42]

Bet the turn. It's more of a "protection" bet than anything. If he calls you should look to check behind river.

I'd fold the river.

He could easily have a flush here too. Why should he be scared of a full house, since you CANNOT have a FH here, given your two checks.

[veryblind]

I definitely agree about a turn bet. It's an easy enough line--if he c/r, i fold. if he calls, and bets river, i fold, if he calls, and checks river, i check behind.

I'm still not convinced it's a flush though. Wouldn't flush want some value? A bet of $15-$20 would probably have suckered me into calling.

It just seems like one of those bets that only gets called by a better hand, unless you've got the absolute nuts and aren't afraid of any call.

[Sharagoz]

I agree on the turn bet too.
The A on the turn was a good card for you. It didnt improve any hands that you werent already beaten by, and it makes it less likely that he has an ace.
Wouldnt he re-raise preflop with AK, AA or KK? Would he check twice after the flop with 77?
I dont think he has any of those hands unless he suffers from the fancy play syndrome.
Most players dont check their flush draw twice either. Not when they're heads up and the other guy has indicated some weakness.

I think he had the pocket 3's. Its the only hand that makes sense when you look at how the hand unfolded. I've seen this play many times when somebody backdoors into a straight or flush, or hit their low pocket pair on the river. The hand suddenly got huge, and the one holding it feels that a big hand should win a big pot, so he then overbets the pot.

Pot odds are 7 to 4, or 1 to 1.75.
This means that you need to be more than 50% sure that he is bluffing if you're gonna call.
Im not sure what I'd do since I would have bet the turn in the first place. I guess I'd most likely fold unless I had some kind of read on the guy.