I read a post on a forum somewhere (afterdawn? cant remember for sure) where a guy was discussing Microsoft banning people playing their copies of Halo 3 that Argos were selling a week before the actual release date (due to admin errors - remember that?).
Anyway, as he said Microsoft were going to ban ANYONE playing Halo 3 (wether it was legit or not) offline as when next time they logged on they would get the persons recent playlists (with times / dates etc), scan them for Halo 3, and if seen before the release date, bye bye see ya later sort of thing.
Now this guy seems to think that he made a new gamer profile on his `box which he played Halo 3 with whilst his network cable was unplugged, and which he deleted (and cleared his cache) before he went back online with his normal profile. He reckons that worked for him and he`s still OK on live etc.
So im guessing this is a similar thing to what your askin, and PLEASE dont take it as concrete cos im only repeating what someone else wrote (for all I know he was taking the piss). But if your asking for thoughts on it then theres one for ya!
Personally, I dont think it would matter wether you deleted the profile or not as they ban the BOX, not the profile. So if you have a box with 2 profiles on and have been banned using one of them, you still cant use the other can you? The whole box is banned so that says to me that they record info on the whole thing, not just per profile. But I may be wrong, anyone got anything better to add?!?