IMHO, sellers like this are already broadcasting that they have no credibility - you have to learn and look. The signals at this low level are not very subtle. For example, I posted "forgery" w/o even looking at the autograph based on the confluence of "Forensics" and "Billy the Kid"...it was a safe bet in this instance ;)
While PSA is not a joke, they are imbeciles as well. So is Beckett., IMHO.
I'd try and learn the signature yourself and use people who know more than you on the boards. Paying those jerks is just foolish when they are embroiled in scandal after scandal. Even though they are the lesser of all other known evils, like this nut job.