Counting Machines Too Good?

Counting machines are getting much better these days at spitting out a lot of stuff that isn't a US coin of proper dimensions. Machines in the US have tech that can detect and reject silver and steel (as well as other magnetic metal) as well as misshapen or physically damaged coins.

This even filters down to consumer machines like CoinStar, I had a crud covered penny that just would not go through so I left it for the next guy in the reject bin after refeeding it a couple times, same for a couple bent coins and one with a decent gouge in it. I have seen a few holed coins go through so maybe they don't look for these as close.

While certain foreign coins still make it through since they are close to the US in size, shape and composition they are pretty good at filtering them out. I often get older copper Canadian pennies in my rolls since they are not rejected like the steel ones are.

I remember reading an article some time ago about a central processing facility for CoinStar and it said they still get a lot of fluff and it gets filtered out there before re-entering the stream after rolling so there are a couple levels of filtering. I suppose they run them through the Mint's damaged coin program recently in the news.