ShowEQ wasn't really bannable as it didn't modify anything as it just sniffed packets. It used to tell if a mob was wielding a weapon or not. So you could tell if the ghoul lord had a sword or not. That is how it determined what 'loot' a mob had.
Well, use of any third party program is a bannable offense. In the cast of ShowLoot, it was something that was originally sniffable, but was later changed to a server side check only, with no way for players to get that information.