SB: $24.85 - tight passive
BB: $23.70
Hero (UTG): $26.85
CO: $83.20
BTN: $10.35
Pre Flop: ($0.35) Hero is UTG with 4 
4 
Hero raises to $1, 2 folds, SB calls $0.90, 1 fold
Flop: ($2.25) 2 
4 8 
(2 players)
SB checks, Hero bets $1.50, SB calls $1.50
Turn: ($5.25) 6 (2 players)
SB checks, Hero bets $2.75, SB calls $2.75
River: ($10.75) 3 (2 players)
SB bets $10, Hero calls $10
Passive player checks the flop to the pfa, it doesn't mean anything. I'd bet a bit more on the flop for value, i don't think his calling range changes if we bet $1,5 or $2. Random PPs, overpairs, sets, flushdraws+overcards are all possible holdings for a player that doesn't like to raise.
When he checks again on the turn it still doesn't tell us much, checking is just what passive players do. I would bet more again, probably something like 4$.
When he donks pot on the river it becomes tricky history of him doing that before. I think it's most likely a "i should have raised before to get more money into the pot but i don't have a raise button so i'll just donk pot now" bet. If he is tight he shouldn't really have A5 or 55 there, but passive players peel super light with a GS sometimes so i wouldn't discard it entirely. If he had A5 or 55 with a heart and picked up a flushdraw on the turn it's certainly possible. He could have two pairs but i wouldn't expect him to got nuts with it.
I don't really see him bluffing in the spot too often, the only obvious draw got there on the turn. So unless he had a small piece of the flop, picked up something more on the turn and then decided to bluff the river when he missed, i think he's mostly doing that with badly slowplayed stuff, most likely a flush, a straight and maybe a set. Unless he has exactly 22, our set isn't much better than top pair in that spot, we're using it to bluff catch.
Most people would think it's very weak, but I would fold it on the river. We beat passive players by valuebetting them to death, when they wake up and start firing pot at us it's usually time to bail.
I decided to call based on two things..
1) I've been showing aggression throughout the hand, if he had a strong made hand couldn't he just check raise the river knowing I would probably value bet.
2) If he's got a weak hand he could bluff to win the pot and I see this line played by passive players against my TAG style often - especially so on dangerous boards that wouldn't seem to hit my UTG open raising range. He can also avoid showing down his weak hand, and I've been fairly tight so it's a possibility. He did just call preflop.
1)
These players mostly don't have a raise button. When they get to the river and realize the pot is small, they don't think about what you would do if they check. They are just afraid that their flush won't make them much money if you happen to check behind, so their fire pot and hope you call.
2)
Your turn bet shows weakness and makes him more inclined to bluff you. I would have bet the turn stronger, so i could be more confident in my river play.
Also you've labeled him tight-passive, so checking and calling is the bulk of this player's play. He could very well have 88 and played it just like that, i see it happen quite often. After that you're not really sure what to do against that guy with your TPTK because he plays sets and bottompairs the same way : c/c.
Showing down a trash hand and dealing with metagame consequences probably isn't much of a concern for such a player tho, i wouldn't overthink it.
I'm just giving you my opinion based on what i've seen. If you noticed on you poker site that these guys are always bluffing in these kinds of spot then by all means just call them down.
I'd bet more on the flop and turn
river is very close, he often has there higher set or flush or straight, so I think folding is fine there, atlhough call is also ok
