Serial killers are usually a bad thing, in any context. Of course, if you were referring to Wyrmtongue, then no, he's not a serial killer. Just like many runners, he gets paid to kill sometimes. Actually, under UCAS law what he did in those trids isn't even murder. It isn't cannibalism, either, since he isn't metahuman. And as far as morality goes, it isn't something he's proud of, but he got paid, and got a nice large meal out of each one.