Renton, I'm not saying it definately applies in this hand, but it can often be correct to call when you are either crushed or a marginal favorite. IE when you have an overpair facing a line that looks a lot like a set/big draw. Say you're getting almost 2:1 though, and you favor the draw. That would be an easy call. Similar reasoning can often be found preflop in low M tournament situations where you're either a marginal favorite or a big dog, but pot odds dictate a call.

In this particular hand, he insta-called so I knew it was either a set or top 2. Turn blanks, river brings a black 2 and I scoop when he shows QT.

I think he would sometimes call here with a Q but I'm not really sure. I think he'd likely call with AQ and likely fold KQ (again, not sure). I think it's highly unlikely that he'd muck anything better like KK. He'd also call with pretty much any draw that he raised and that's certainly not unlikely. I also think I will get the very rare call with a made hand worse then top pair but I think that would be a rare exception.

Oh yeah, and, he opens such a wide range from the button here and pretty much auto-raises whenever I lead, so the fact that he woke up with a hand that was > AA is a semi-miracle in itself. I've practiced pairing the board on the river for countless hours though. Usually I reserve it for set--->boat over flush, but there's nothing wrong with doing it on occasion to over 2 pair someone.