Most of the offensive names don't last too long, although some get by. It depends upon how often that account gets used on games over Live. I would wager it's one of the most used feedbacks out of all of them, mostly because a legit bad name doesn't require looking over what transpired in a game or what some people say happened. I bet after a while most of it ends up like this...
[Cursing]
XBL Rep: "Hmmmm...lots of complaints, so it could be true. I guess we'll fire off the ol' warning e-mail to this guy and let him know what's up and all."
[Bad Name]
XBL Rep: "Hmmmm...lots of complaints. Let's see...ifeckgrannies...yup, that fits. Off you go, little 2-monther! See you in a bit!"