Noun- when a man does not have a fully developed mustache, instead he has peach fuz like hairs, that are usually dirty, on his upper lip. Most commonly seen on mexicans, 11-13 year old boys, and people who are down right hideous.
wow hes been trying to grow out a mustache for weeks and all its turnd out to be is dirty scumstache
(noun) - a mustache developed by prepubescent boys that resembles a smudge of scum across his upper lip. they can usually be found on Chibi Kuririns.
Chibi, go shave that wretched scumstache.
(noun) a term used by someone who doesn't have any better of a comeback to use, usually used by prepubescents on AIM with SNs beginning with 'roffle'
roffle needs to shave his scumstache more often imho