My reading comprehension is fine, it's just that about the only arguments he finds to be ad hominem are those claiming ad hominem.

Although the article could have been much shorter if he simply defined ad hominem as "You're an asshole and therefore wrong."

After misunderstanding such an obvious joke, I must disregard your argument as false.

PS: recursive ad hominem?

I was just kidding about the reading comprehension. Mostly.

Here's an example he gave of an ad hominem attack that doesn't involve calling the other person's attack ad hominem:

   A: "All rodents are mammals, but a weasel isn't a rodent, so it can't be a mammal."
   B: "Well, you've never had a good grasp of logic, so this can't be true."

and here's another (from the Nick Naylor school of rhetoric):

   A: "All rodents are mammals, but a weasel isn't a rodent, so it can't be a mammal."
   B: "I'm sorry, but I'd prefer to trust the opinion of a trained zoologist on this one."

Yeah, I get it. It's an article about ad hominem, so the joking insults come out.

The first may not actually be ad hominem. If A actually doesn't have a good grasp of logic, then there is no attack just a statement of fact. And he actually says the opposite earlier, but with the statements reversed (This can't be true, you don't have a good grasp of logic.).

And the second is argument from authority, not ad hominem.

Lastly, ad hominem doesn't always address the argument. In fact ad hominem is an abandonment of argument in favor of abuse. You start appealing to people's emotion by painting a negative image of the person.

He said: "Well, you've never had a good grasp of logic, SO this can't be true."

Which is the same as saying: "This can't be true, BECAUSE you've never had a good grasp of logic."

The problem with ad hominem attacks is a broken clock can be correct twice a day or more. So saying the clock is broken does not necessarily imply that it's wrong now just that it has been wrong in the past and will probably be wrong in the future.

When parsing arguments look for words like and, or, because, so, thus, etc as they are the foundations of arguments. You can add a lot of meaningless drivel around the core argument but as soon as someone starts tossing those words around they are probably trying to use logic. His point is the way an attack is connected to the argument determines if calling something ad hominem discredits the argument.

PS: People sometimes add an ad hominem attack as part of other more rational statements, so IMO attacking the person even alongside a rational argument is still an ad hominem attack even if it is not used to directly attack their argument. However, simply calling part of what someone says an ad hominem attack does not destroy the rest of the argument if it's not directly linked to it. It's like a defense attorney that counters the DNA evidence but ignores the video tape and the confession is going to fail.

The problem being is that not having a good grasp of logic can cause you to reach wrong conclusions. It can be a direct cause. In which case, it is a valid point to bring up as it supports your argument.

Knowing the cause is useful, but to discredit someone's argument you need to find the mistake. Think million monkey's typing for a million years randomly recreating Calculus. The source is dumb but it works.

How about, "Apparently, there was a failure in reading comprehension that preceded your reasoning."

Is that quip about "Reading Comprehension" directed at me?