Yes, as I said, they do end up there either by accident or by collectors intentionally dumping coins of low grade that they don't need... or even if someone has stolen a collection and spent them in circulation.
Hey I finally got me a 2010 nickle today! I got it, it's a 2010 d, a '64 p half, a 2009 p cent, and 2 of the new california quarter which are also d. I got them while I was checking at work today.