Level?

This is such a standard call-as-fast-asyou-can snapcall, that you might wanna analyze more hands

Is it? What do you expect to be ahead of then? I think the runout, his sizing and his playing style so far make it very unlikely he's bluffing or valuebetting worse. If I give him $FI20 OTR, any Ax still makes up ~22% of his entire range and it's still a fold if I give him half of his QQ and a third of his JJ combos.
Remember that at these stakes recs a) bluff way too little, b) don't valuebet thinly enough c) frequently check/trap strong hands on early streets than you might be used to at your stakes. I could be convinced, that this is still a +ev call but I can't see how this is not close. Which part of his range do you think I underestimate then?

If villain's a passive fish who literally bets nothing until the river and then full pots the nuts and nothing else - and yes there's lots of them around at micros. Then easy fold.

All other villains - snap call - as it's very clear by the river you don't have an ace.

call , unlucky u lost to quads

Fold sounds right given villain description

Lol at ever folding, against nearly any opponent I am raising river for value in this spot. Player reads aside card removal alone is enough to justify a never fold.

I think villain is polarized here between bluffs (with like worse turned boats that now can't win) or Ax/KK. Can't see QQ and below valuing their hand this much here. Given the action I don't think he really pots the river very often as a bluff either.

I know a lot of you would expect villains to bet all their good trips/boats on the turn but really, these monkeys love to check raise and some will only check call without the absolute nuts

Raising with a bluffcatcher on the river vs. a polarized range is lolbad

I think it's close but you probably win the pot 33% of the time here with KK, so call. Folding is the correct play if you think he'd rarely pot the river as a bluff (river pot bets at micros are like 94% the nuts).

Considering you're blocking one of the only hands most villains at this stake would pot for value that we don't lose to, I have to disagree with this. In general at 25PL and below villains pot betting ranges are extremely value heavy. You can literally just exploit them all by never calling their value bets. Card removal is less of a factor than totally unbalanced ranges

Wow I would just snap call and not think twice about anything in this spot.

Would consider betting turn for protection though.

Glad river bet isn't a lot smaller since then we would suddenly have to start thinking about raising.

Calling is standard in this spot, folding is an option, and raising is horrendous.

Probably is a fold with your specific read. A "very passive player" just isn't potting queens or less for value and is rarely bluffing. Really not all that rare of a player type IMO.

vs really nitty regs I might fold vs everyone else just instacall and move on to the next hand.
And I think I would cbet flop or atleast the turn.