You could get a thrill by listing a gray item at the gold cap… No clue why, but on infrequent occasions I see crazy mispriced stuff and just assume it’s a 12-year old excited by all those zeros! 
TSM will show the sell rate of various items on your server. A lone listing with no sell-rate info means a very low chance of an actual sale (thus, doesn’t matter what the list price is, since it’s probably not selling anyways).