Nick Corcodilos ("Ask the Headhunter") just addressed this question in recent newsletter. (If you haven't signed up to receive it, do it! For those of you who don't know Nick, he spoke at the NRWA conference in Scottsdale a few years ago. He's generally positive about professional resume writers, but down on "resume mills.")
Here's what Nick said:
"My advice: Edit your resume to make it relevant to the employer, and make it as long as it needs to be. Make sure it's long enough so it reaches where it's supposed to go."