Yeah, I think there is actually WIP to do something along the lines of what you worked out. However, I'm not sure what good identifying "suspicious transaction

Yeah, I think there is actually WIP to do something along the lines of what you worked out. However, I'm not sure what good identifying "suspicious transactions" is going to do. They're not reversible. You can't really make any attempt to "blacklist" them - you'll almost surely lose.