It's exactly as you said it. The score remains from the moment that the address is tagged as "shady" or "blacklisted". The problem is that you can't get rid of it, no matter what you do. At least as far as I know.
This makes me wonder what is going to happen if let's say 70% of the Bitcoins in circulation are marked/tagged as shady or dirty. The would AML score thing is just going to make people fear using Bitcoin at one point for fear of having their funds frozen by exchanges because they acquired "dirty" ones.;