i check to you - you fold...on the river?

[asofel]

I was playing a few hands before work this morning (yes, addicted, i need help) and something strange happened: I was betting out on the flop (HU), on the turn, and after being called down the whole way I pulled up and just checked on the river. My opponent folded....

Now, he left right then, so perhaps he just closed the app real quick, maybe he was disconnected, I don't know, but it got me thinking.

When would you fold if checked to on the river? Ever?

If so, what would the reasons be? Missed badly on a draw you shouldn't have been on? Know you can't win and don't want to give further info away?

I'm curious if anyone's ever seen this done by an intelligent player...

Thoughts?