Their checks on the turn are weak. I think you have to make some sort of large bet there. If someone raises you and its not too much I'm calling and hoping for a boat/quads. If its a huge raise I'm out. The 6 actually isn't that scary since someone would have to be calling with an inside straight draw on the flop, more than likely someone just paired their sixes, its the flush you should be worried about. That river is about the worst card possible. I'm check/folding after that 8c hits.