The tone argument? Doesn't apply if the topic is not oppression, mk. If I am flinging myself ragefully at someone over their characterisation of Filch and they tell me to GTFO because they don't want to talk to such an angry person, I don't get to turn around and be all "way to rock the tone argument, bitch. >:O!" at them. Don't fucking conflate annoyance with some aspect of a totally frivolous issue with anger/rage borne of actual real life suffering.
HOWEVER. The presence of emotion (positive or negative) in a discussion never invalidates that discussion all on its own.
Ad hominem arguments are, broadly, ones that attack the person and not their assertion[s]. Expletives and sarcasm alone, however, do not make an argument ad hominem.
"You've never even had a pet; how would you know what Mrs Norris's behaviour says about Filch's treatment of her?"
"Well of course you'd think that Filch neglects Mrs Norris; you've had what, eight pets, and they all died of neglect, didn't they?"
"What you say about Filch here is wrong because you are an idiot."
"You're not a veterinarian, so you're wrong about Mrs. Norris's incontinence problems."
These arguments are all ad hominem and fallacious because even if a speaker is less experienced, a hypocrite, or a fool, it does not preclude the possibility of him or her making a sound argument (case in point: Eureka's Jack Carter). Using someone's personal history to discredit their claims has nothing to do with logic.
It is not unreasonable to suggest that someone's inexperience in a given field means their claims do not stack up against the words of an expert in that field, but it is not logical. It is not logical to claim that someone must be wrong about a medical issue simply because they are Not A Doctor. It's just as illogical to claim that someone must be right about a medical issue simply because they are A Doctor. People, including Nobel Prize-winning doctors, can always be wrong, even about their area of expertise.
(Aside: Note that "area of expertise" is quite different from "personal experience". Personal experience is a body of knowledge available only to one person, whereas area of expertise usually refers to a body of knowledge accessible to more than one person. To say "you're straight, so you don't really know what it's like to be gay" is not argumentum ad hominem. It's a fact. It is presented as an argument, which can be confusing, but it is a simple incontrovertible fact that a straight person, due to never having had the actual experience of being gay, does not really know what it's like to be gay. It's not a value judgement, even though a lot of straight folks seem to take it as such. It's just as inaccurate to claim to know what it's like to be queer (when you're straight, no matter what your level of exposure to the LGBT community) as it is to claim you have had the experience of working as a police officer when you've only ever heard about it/read about it/seen it on TV (even if your mother/brother/best friend is a police officer). It's not a logical fallacy. It's a factual inaccuracy, because in the case of this kind of knowledge, nothing trumps first-hand experience. People can and very often do use their personal experience to make logically fallacious or factually inaccurate claims, but that's a whole 'nother bundle of sticks.)
"Are you an idiot? Filch's cat is named Mrs. Norris!" -- this is rude, but it is not ad hominem.
"Filch clearly neglects Mrs Norris, and if you don't see that, then you are an idiot." -- also rude, but not ad hominem. It doesn't imply that the assertion is wrong because the speaker is an idiot; it says that the speaker is an idiot if he doesn't agree, which is not part of the argument itself.
There is no requirement for logic to be dispassionate. That logical beings (or regular beings attempting logical reasoning) are usually portrayed as near-robotic in most fiction is simply a reflection of the vastly under-reported and pathologically underestimated mistrust of science and reason that even now prevails amongst humans. It doesn't actually have anything to do with logic and how it works.
Fandom does so much ~shaking and crying~ over "personal attacks" when I think a far worse problem is the abundance of people who think it's perfectly logical to say things like "you've never written anything in your life, so you can't possibly have anything worthwhile to say about
Carry on. You bastards.