I tend to think most pk'ers I see are actually above par RP'ers, comparitively speaking. I just think its a common problem amongst people from RP muds that they expect to be warned that they're going to be attacked. They expect a grand dialogue prior to and following every interaction, and CF really has never worked like that.

The element of surprise is an important one, and my orc isn't going to explain to you why he's going to walk up and kill you. He's a savage orc, he's not walking over to hand you a knit area rug.

Anywho, its a typically recurring theme that "I didn't get warned I was going to get attacked" = "bad or no RP".