Given that Villain is a rather tight-passive player (VPIP 22, PFR 2, AF 1.8, 3bet 5.0), this River card that River was perfect to bluff against his range. Should I have bet slight higher here, about half the pot? What is standard theory now about bluffing OOP on "good" cards in our range?

What are you trying to represent? A flush, a 10?

Your villain bet 64% of the pot on the flop. You bet like 35% of the pot on the river, trying to represent a flush I'm guessing.

A strong flush draw might lead on the flop or re-raise, or bet on the turn to try and take down the pot there. Even if played passively, you would be looking for more value on the river if you hit a flush and the bet would be as big as possible to extract value. So your bet is too small... He has to put in just $0.46 to win a pot of $1.77 and you know he must have a strong hand. Your best hope is actually that he has AK (not suited diamonds), because that's probably the only hand in his range that will be likely to fold. Maybe JJ as well, I suppose.

I would also be thinking about blockers. You don't have any diamonds that would help your flush bluff. If you had the Ace of diamonds, for example, that wouldn't be in your villain's hand and therefore he would have to think that the nut flush could actually be out there.

I also feel like facing a 3-bet pre-flop means that the chances of your villain folding to a bluff are diminished quite a bit.

I was trying to represent a weaker flush, like KQ betting for value.

As I put him on a big hand like KK-JJ, a possible AA or AKx-AQx, I thought it was the bet spot to try a last ditch effort to win a big pot at a cheap cost.

Those preflop stats are absurd, how big is your sample? If the sample is significant, I don't see much use in trying to bluff a 22/2 villain who 3bet our 4x UTG open (which I also wouldn't suggest doing) and bet the flop. As was said, your fold equity is going to be pretty minimal vs such a tight range, especially with that sizing. Plus that river is pretty good for villain's range too, not just yours. Having a blocker would be pretty relevant here.

I have checked back my hand. Indeed, wrong Villain stats, my bad. It was VPIP 22, PFR 20, AF 1.8 over 61 hands only, 3bet 5.0. So 20 PFR, not 2 PFR.

AJs plays so bad when 3betted IP. Yes, equity-wide we have 37% against a 5% 3-bet range, so calling here is mathematically sound. However, unless we hit JJx, AAx, KQT or a flush draw this hand is mostly a dud to play OOP against a 3bet.

I must admit, I barely understand the concept of blockers, nor do I know yet how to use that knowledge. In my mind, having AJ does not make it magically more difficult to face another Ax somewhere when we are not in a HU game, especially when having A-something makes it likelier for Villain to call behind somewhere. I have seen enough AK vs AA, or AK vs KK, or called down Axx with A-rag rationalizing that chances are small he might have another A with two being visible, only to find myself against AT+, to know that if he has it, there it is, blocker or not blocker.

But you're betting less than your villain probably would have bet left to his own devices, so why would he not call?

I mean the point of a value bet is that it gets called and you get value. You made a bet that if you actually had the hand would get called, so why would he suddenly decide to fold in this situation? It makes no sense to me.

I don't actually think if it was a value bet it would be a very good one, because you could easily make a larger bet (say just under pot size) and he would still call with his hand and you would get more money. Particularly at these stakes. With a big hand like a high pocket pair, it's going to be really, really difficult for him to lay it down.

fold pre

floating OOP on a 3b pot on a utg vs co dynamic is not profitable too say the least *cough *cough* burning $$$

glgl