[swinglock]

If you have to explain where it's from it may be more suspicious if it looks like you took steps to hide the origin, calling for even more detailed proofs.

[aeternus]

Does any currently operating exchange actually care about the origin of coins?

[ar4s]

Most of them [exchanges]]will have tagged stolen coins from known hacks so when they are deposited the account is flagged/locked.

Tumblers/mixers are the most likely place to pick these up.