[pohuist]

If you ever C/R the river his may be a really good spot. I am split almost 50-50 here but probably still leaning towards bet. If he's smart enough to know that you know he has a flush, he should also be smart enough to smell a trap. Especially, if he has A-high flush, the possibility of you having Aces has significantly diminished and he must suspect QQ or KK. (Are you paying off here w/QQ and does he know that -- if you are not, there is no point for him in betting) Furthermore, he could have called A-Js (non-spade obv)and decided to wait till river to evaluate. He will call but not bet the river. Finally, he may have oddly played JJ and will give you a lot of action. I think, against a thinking player, coupled w/a possibility of him not having a flush a bet is slightly better, but neither is particularly wrong.