It may be mixed but then people can trace that the BTC comes from an exchange. It serves but that will still be an issue if the person is going to be traced deliberately when the BTC comes from a known exchange address.
Yes. It's not proper mixing. All I'm interested in is making sure future transactions can't be traced back to my original wallet by any old creep having a look. I don't care if they know it's from an exchange and I don't care about the exchange itself knowing the original address.
If I were a paedo, drug dealer or thief then my approach would have to be totally different.