It is my understanding that libel is only libel if you are aware that it is a lie. If the blogger was honestly convinced that this women was a skank, then the blogger would be be guilty of defamation...
If I claim someone is a drug-addled buffoon, that may be defaming, if that person is Ozzy Osbourne, then his corpus of work speaks directly to that conclusion and only the most highly paid lawyers would bother to argue that description defamed him.