One of many, many so-called logical fallacies is ad hominem–“to the person,” short for argumentum ad hominem.
That link is to a Wikipedia article, and in this case (as in many others, although not always), it’s a pretty good discussion. If you read it, read the whole thing–including the Talk page (which I always recommend reading if you’re using Wikipedia for anything more than quick lookup).
I find it interesting that some academics and philosophers argue that ad hominem isn’t a fallacy at all.
I won’t go quite that far. I will say that some things that can be faulted as ad hominem are really something else: Learning from experience.
Viewed through the prism of long experience and various arw–sorry, awkward–attempts, it’s not unreasonable to be deeply suspicious of new initiatives from old antagonists emerging to a chorus of selective praise from the usual suspects.
That’s not ad hominem; it’s learning from experience. It’s learning that, based on oodles of previous cases, you should view proposals from certain parties with extreme skepticism, even reasonably beginning with a stance of “demonstrate that this isn’t another trick” rather than “sure, sounds like a good idea, let’s investigate further.”
Technically, it’s true that just because an agency or group or person has been wrong 100 times doesn’t mean that they couldn’t be right the 101st time. But saying “well, you can’t judge the future by the past, so you have to give them the benefit of the doubt” is just silly–and calling an inclination to judge the future by the past argumentum ad hominem is equally silly.
I won’t claim that I won’t get fooled again–that would be as absurd as hoping that I would die before I get old. (A bit late for that by now!) I will claim that I’ll apply substantially more critical analysis, looking for loopholes, questioning underlying motives, assuming the worst…all those nasty things…to proposals coming from parties and groups with long histories of suspicious proposals.
If doing so is a logical fallacy, so be it.
I’m fairly sure this is where ethos comes in as a handy concept. You do have some right to look at who is saying the thing as well as at what it is they say.