Eh, while recognizing the ad hominem has value, so does bringing up the credibility of the people bringing the charges. To choose an example more dear to HN's

Eh, while recognizing the ad hominem has value, so does bringing up the credibility of the people bringing the charges. To choose an example more dear to HN's heart, just because someone is being sued by a notorious patent troll who has lost numerous court cases when the people they're suing don't roll over, doesn't mean that the case is without merit ... but it definitely shifts the Bayesian prior in that direction.