The Urban Dictionary has several definitions (warning: link contains some vulgar language), including:
A term commmonly use to refer to a young woman (or sometimes male) describing un hygenic habits, very little clothing and usually hints at that they are “easy”
A derogatory term directed towards females, usually young, suggesting sluttiness, lack of hygiene, poorness, cruelty, tackiness, or use of drugs/alchohol/cigarettes.
a really trashy chick who is either unclean, slutty, or both.
A person, usually female, whose attempts at vanity result in a used, vulgar, or unhealthy and lewd appearance.
Like a slut, but with connotations of nastiness.