After meeting with one such recruiter, f13.net forumite Tale relayed his experience:

He replied that employers specifically instruct him not to send them World of Warcraft players. He said there is a belief that WoW players cannot give 100% because their focus is elsewhere, their sleeping patterns are often not great, etc. I mentioned that some people have written about MMOG leadership experience as a career positive or a way to learn project management skills, and he shook his head. He has been specifically asked to avoid WoW players.

The recruiter in question was apparently working within the "online media industry," though no details were mentioned as to which employers he works with.

In the past, some have felt so strongly about the benefits of MMO experience that they've suggested players list that experience on a resume for applicable companies.

Thanks to Boing Boing and Raph Koster for the heads up.