Similar to a filthy girl, this person is not only the embodiment of horrible temperment, but is also just as promiscuous. May be a current or former stripper, and have more than 4 kids. Said person may or may not be easy on the eyes, but is convinced the (s)he is God's gift to (wo)men. This person uses all relationships, regardless of nature, to be as conniving and manipulative as possible.
Although it is a neuter adjective, it is most often used to describe females as opposed to males. Males of this type are most often referred to as a dirty douchebag.
I moved in with my brother-in-law and his girlfriend. She turned out to be the biggest megabitch filthy hobag. She acted like she owned everything, regardless of whether or not she actually did. She was manipulative, selfish, and judgmental...the keyword being mental. Needless to say we moved out in about 3 weeks.