Isn't this the crux of infamous "ad hominem" argument: attacking the person instead of their reasoning?

Even smart people sometimes make stupid arguments.

And good arguments can be made by anyone.

It's very difficult to be right 100% of the time.

It's also quite unusual to be wrong 100% of the time.

Evaluate the reasoning, not the author.

Stupid argument, not stupid person.

Look at what Alsup said to Boies.

Still, this is easier said than done.