I'd think that most killers get off on the victim's screams, pleas for mercy, moans and whimpers, which zombies couldn't really produce. The fun of being a serial killer is what you do to the victim before you kill him/her, not after, with the exception of the rare cannibals.
I think they would have initial fun but get bored quickly. They would begin to hunt the living. It would be more exciting because they are rare and armed and on guard!
Well they may not enjoy it as much but could they get by? Young Dexter hunted animals to keep things in check.Would it be like drinking rat blood in interview with a vampire? or true blood (fake blood) in the show True Blood?
Maybe if they were screaming zombies...
I'd think that most Serial Killers like to live as long as possible, so as to continue their Depravity. So, killing off the Living in a Zombie Apocalypse would actually be detrimental to their continued Existence.Of course, it would be Poetic Justice if the Serial Killer claimed a victim, then was delayed, and upon returning, had to face a Fresh Zombie.
Any Comment may be nuked from orbit.