Green’s Dictionary of Slang

(US campus/teen) anything, or anybody, seen as repulsive, disgusting.

1990		Eble Campus Sl. Apr. 7: skaintch – extremely negative. ‘That new Milli Vanilli record is pure-t skaintch.’.
2002		Teen Lingo: The Source for Youth Ministry 🌐 skanch (adj.) repulsive and skank-like (see ‘skank’) ‘your girl ain’t nothin’ but a skanch queen!’.