I think if you bet the flop, maybe around 2/3 of the pot, you might have a better idea if you are ahead, behind or in position to join the masses who go up in flames with top pair/top kicker. KK, QQ, maybe not KQoff could be behind a big re-raise preflop on an early hand and possible lurking donkies. I sure as hell wouldn't raise on the river. You gave nothing more than a gut read on calling his river bet which looks like a milker in my opinion. What happened?