From Love-shy.com wiki: A wiki for the dating-challenged
Celebrity evidence is that which is used to prove a point by using a celebrity as an example of said point. When used to support a point, it is a fallacious form of evidence, as celebrities tend to have immense popularity, notoriety, wealth, or a combination of such things.
Celebrity evidence is often used by personalitists in an attempt to disprove the claims of looksists. By posting images of celebrities who are overweight or otherwise physically unattractive with attractive girlfriends, the personalitists hope to disprove the looksists, or at least hope to make onlookers question their claims. This evidence tends to do little more than confirm the biases of those who are sympathetic to the personalitist camp, instead of rigorously refuting the looksists' claims.
Celebrity evidence can also be used by looksists in an attempt to prove their points, but falls flat for the same reason. As an attempt to validate the looks ladder it fails due to the reasonably high number of unattractive celebrities.