AK (aka I never fold)

[JonTheFox]

if it's bluffy opponent, we're calling down because of the combined chance that he is bluffing and that we will outdraw. we shouldn't be calling down if we think our ace is counterfeited and we shouldn't get fancy on the river if we think our ace is counterfeited.

against an unknown opponent, I call down and then it's maybe 50-50 for me between donking the river or just check-calling. If he is a decent player, he's going to check-behind with a hand like a medium pocket pair and probably fold to a bet...if he's a bad player, he's going to bet and fold to a raise so you still only win 1 bet, unless of course he has you beat and then you lose more than 1 bet

[New001]

Not looking at responses, so I'm sure this has been said already. Check/raising the river seems terrible, especially if you're going to pay off his 3-bet. I'd probably bet/call and consider check/calling.