[mystro]

unless you've seen villain bluff river before, I think you can safely fold here. Villain may think your bet is weak, because it is, but a villain with aggression factor of 1 doesn't check raise here often enough for this to be a bluff call, and with a paired board, you're behind to essentially everything :S

As a slight aside, I think after the turn check/check I would resolve to check/calling a small bet here, the 6 clearly didn't improve your hand as it is unlikely that you raised $1.5 from the SB with 66, so an observant UTG will know that, and combined with the weak bet will know that you can likely be taken off your hand