Very interesting topic indeed.
The word "skank" is used to describe a person (originally a woman or girl) who is considered dirty or diseased because he or she is promiscuous or slutty. It is implied that a skank spreads sexually transmitted diseases. You may also hear "skank" used as an adjective to describe a thing or a place. As in, "Dude, that bathroom is skanky."
The roots of the word skank are slightly unclear, but it may come from the word "skag", a word that originated in the African-American community in the 1920s to mean a dirty, unclean woman of questionable repute. "Skank" is also a type of reggae/ska dance in which the dancers bend at the waist, and flail their arms in the air. The gyration of the hips during this dance may have lead to views of women who danced in this style as knowledgeable about sexuality and therefore "skanky." Either way, the term is racially charged, though that aspect of the word seems to be largely forgotten or ignored these days.
Personally, I think that skanks are overrated. My Ma sometimes says the women I bring home are skanks. I think they're just misunderstood. Doesn't matter to me. Just as long as I can have my brewski.
Cheers!