river c/r bluff (?) (online?)

[OTRise]

The only hand you take him off of is possibly AQ. Other than that, he isn't betting another lone ace for value. So, he either has a missed draw, aces up, set. Aces up and a set are probably making a call just because a river c/r looks fishy, so your basically trying to clean up a little extra money off a busted draw, which if that the case, its better to just fire out a strong bet risking 500 than 1500. Unless of course, you have him tagged as betting rivers light like with AJ etc, or middle pair+draw trying to take you off an ace.