How about adding a new thief skill...disguise?
Allows for a thief to temporarily take on the appearance of another race or player. Gnomes couldn't dress up as a Minotaur...so player size would have to be a limiting factor. The disguise lasts for x number of ticks or combat rounds with a % chance of the disguise instantly falling away when combat is initiated.
Clair/door/relocate wouldn't be fooled by it, but look, scan, track, and even the who list would reflect the disguise if successful. Like sneak/hide, the thief always thinks the attempt is successful. Even so far as to appear to be disguised when looking at oneself.
Format might be disguise elf to appear as an elf. Helps with getting into certain zones or for zones that are agro certain races.
For players : disguise player name to take on the appearance of another player. Perhaps make a limit that the player you are trying to appear as must be on line, and you must have a successful look or case prior to attempting the disguise.
Could be fun and cause a little mayhem.