So here is a hand where the results are alluded to, but I am looking for a more general discussion of how you process these decisions.

The game is 2-100 spread limit.

The PFR is a huge tagfish, who raises preflop with good hands then plays horribly postflop. The player in BB hasn't done anything remarkable but is somewhat loose.

PFR stack is ~$80, hero and bb have $200ish.

Hero is in SB with Q T
2 limpers, PFR makes it $10, Hero, BB and limpers call.

Flop ($45, 5 players): K73
Checked to PFR who bets $14, hero calls, BB calls, others fold

Turn ($87, 3 players) 4
Check to PFR who bets $20, hero calls, BB thinks then calls

River ($147) T
Hero checks, BB somewhat quickly bets a stack which is exactly $40, PFR folds, hero...?

Now I realize you might've played the hand differently on earlier streets (comments welcome) but here we are on the river with 2nd pair and an odd bet by a loose player.
What is going through your head?

I'll tell you one mistake I made was not computing the pot size ($187) or my pot odds (about 4.5 to 1).

Fold pre; stacks are too shallow to play a likely dominated hand OOP.

Flop and turn are fine given such good immediate odds.

I call the river. It doesn't make sense for BB to have a K with his line. I think his range here is pair+BDFD hands OTF, 99, 88, 65ss, some unexpected low 2pair combos, and some other flopped pairs/FDs he might have turned into a bluff. Anyway, we only have to be good 18% of the time, and I think we are.

preflop fold. That's really all there is to say.

Thanks, and I get that out of position with a potentially dominated hand is not a great place to be. I'm looking for some discussion of what to think about on the river. So if you like, pretend I have called in position with the same or a better hand and played postflop the same way.

Thinking on river? BB could have backed into a flush, but could also be betting any single pair here for value. Villain is very unlikely to have any KX or better except the rivered flush, many villains won't have any and the ones that are passive enough to show up with something like that probably check river also. Considering villains range, we actually beat the bluffs and much of what he could be value betting. Bet is small compared to pot, giving Hero very good pot odds. Bet is so small bluffs are actually somewhat unlikely here, but many 1/2 villains also size these bets very badly and make cheap steal attempts here. One additional thing I would be thinking about is villain's betting and play style, but you don't give enough information to have any real opinion on that. This really plays into how often I think villain is bluffing here.

In any case, against most villains this is a crying call. I expect to lose here more then win, but pot odds are very good. Bet is too small to fold a hand with decent value except against a passive villain who is never bluffing, never betting worse then TX and and never has worse then T9. At that point his range is mostly hands that beat us, and we can fold.

Oh, and yes, fold pre. QTs out of the SB is very RIO shallow, only play it when you can complete the blind and only when stacks are deep to fish for two pair+.

Fold pre due to V stack size. As played I prob raise flop to 65 and get it in or hope everyone folds. I like to play my draws fast though.