Hacks? The correct term is trainer.
It is possible for Xbmc to detect that xbes are on the hdd so, yes. But do we want Xbmc to check that files you have on the hdd? Sounds like some good old communism to me, so no.
It is not the apps job to check this, nor will it be. Weither or not some have a trainer on the hdd is fully up to themselves and not any others business.
It is the job of mods and admins. If you see some cheating in a game you take a screenshot, or get an admin or a mod to join in.