This version of the ad hominem fallacy is pretty self-explanatory. When a person is attacked with abusive name-calling, it is their ethos that is being targeted, not the logic of their premise. 

Using this type of fallacy can make the attacker look immature, unfocused, and desperate to the educated audience. 

That said, in an emotionally charged argument, it can further charge those who already support the abuser and, in some instances, can sway the uneducated portion of the audience, distracting them from the actual debate.

Example: 

"Your Honor, it is important that you find Mr. Spagnolo guilty of speeding! He smells funny, isn't handsome, and once yelled at a homeless man."

Example: 

"You don't like CANDIDATE X because of her policy on immigration? Your an idiot."

To be clear, in the last example, I used "your" instead of "you're" incorrectly on purpose. 🤣 In my experience, most people who call someone else an "idiot" on the internet accompany that ad hominem with "your." Surprising? Not really. Just an observation.

One more [real] Example:

"Joe Biden says Climate Deniers A Dying Cohort of 'Lying Dog-Faced Pony Soldiers'"

Circumstantial ad hominems occur when someone's argument is dismissed because they appear to have a conflict of interest. While it is true that they may have a conflict of interest, that doesn't necessarily mean that their argument is without merit.

Example: 

Your argument that the United States is the best country in the world is false because you're from the U.S. and have to say that.

Example: 

Of course Mark Zuckerberg believes governments should pay to make sure that every person has an internet connection; after all, he owns Facebook and stands to make a lot of money if everyone can access the Internet.

Yes, Mark Zuckerberg would make more money if more people had Internet connections, but does this mean that his argument is inherently bad?

Not necessarily. It should be taken on its own merits regardless of whether Zuckerberg stands to make money from it or not. Frankly, because Zuckerberg really understands the uses of the Internet, he might actually have some ideas worth listening to. In theory, it can be an honestly good idea AND it can make him money. Those results aren't necessarily at odds with each other. They are independent of one another.

We've all heard someone say, "Do as I say, not as I do." Well, if we were to assume this advice was wrong simply because the person giving the advice wasn't following their own advice, we would be faulty in our logic. 

We've also seen (used?) the logic that, "Well Sundari did it, too, and she didn't get in trouble? Why are you going after me about it?"

People who use the tu quoque fallacy seek to justify their infraction of the rules by pointing out that someone else has done the same thing and gotten away with it. Perhaps, this is true, maybe they did actually get away with it, but that is completely irrelevant and has no bearing.

Example:

Driver: "Officer, I'm pretty sure I saw you speeding yesterday; therefore, it can't be a crime."

Officer: "Well, I actually was speeding yesterday, but nobody pulled me over. I guess I got lucky. Speeding is illegal. You were speeding. Unlike me, you got caught. Here's your $300 ticket. Have a nice day."

Here's another...

Example: 

"I don't believe my friend, Bob, when he says that smoking is bad for me. He's a smoker, so he clearly doesn't know what he's talking about."

Honestly, Bob might, in fact, have something sensible to say about the perils of smoking.

One more...

Example: 

"How could you call a foul on me? They've been fouling me just like that all game, and you didn't call a foul on them!"

Anyone who has played football has heard that one. Most of us have used it, too!