For me, Colin really was a bad one - he really didn't give a damn. That is why he is one of my favorite guest actors on the show.
These are my favorite guess actors/actresses in order
1. Deshawn
2. Colin Robbins
3. Emily Valentine
4. Lucinda Nicholson
5. Elle
6. Psycho Laura
7. Susan Keats
8. Toni Marchette
9. John Sears
10. Riggs The Pimp
11. Crazy Tara
12. Chancellor Arnold
13. Doc Martin

yes from my list, I enjoy watching crazy nutters. I liked Erica in S4 but not S8, Nikki was OK. But the rest were boring as hell, Tracy Gaylian is certainly one of my worst guest stars along with Mark in S7 plus Dan Rubin. Matt bored the hell out of me, and Gina and Felice were so annoying.