[mythrilfox]

I think not betting the turn was a mistake. It limits your hand to: AK, KK. That's it. I can't imagine anyone checking here with a set or two pair against a loose player, and now you have to guess what he has out of position instead of forcing him to define his hand, while you've defined yours clearly.

Preflop I think he'd have raised an ace, judging by your description. Set or low flush probably bets more on the turn, although it seems like there is an outside chance he has a low flush and is just a bad player.

So either he has the nuts or this is an intricate delayed bluff with the K[img]/images/graemlins/heart.gif[/img] He could also have K[img]/images/graemlins/heart.gif[/img]Jx or something. What do you think? Is he smart lag or dumb lag? Would he take a free card with the lone king? How aggressively does he play with his good hands vs. his bluffs?

Tough spot. Without anymore information I'd just call and try to gauge what he has by his bet size on the river, giving serious consideration to folding. I know this is bad in general against a lag, but just looking at what he might have considered raising preflop, a flush seems like a very distinct possibility.