More importantly, we don't even have evidence that pickup artist techniques work for anyone! All we have are testimonials from people highly-incentivized to make them. Is there any factual evidence that David DeAngelo, Neil Strauss, or any of these PUAs actually have slept with many beautiful women?

Yes. Video evidence and an overwhelming abundance of eyewitness reports. Including reports from women who they have dated. All of this is evidence that someone could assert is faked or engineered by some ingenious plot with payed actors and widespread bribes. Technically.

Anatoly's observations are spot on, whereas MartinB's ignore the problems with self-selection bias, and could also be used as a defense of psychotherapy, ouija boards, and picking lottery numbers from fortune cookies.

If we are going to throw about insulting analogies for rhetorical effect then a more appropriate one would be "moon landing".