Actually I think "Ad Hominem" is a rather good filter.
Although it's not a proof of statement being true or false, it's still good to ask your self a question "why is this person saying this?"
For example: A stranger rolls up in a truck up to a kid on their walk from school and says "get in my truck, your parents were in an accident, and I need to drive you to hospital". Now all the person said could be true - but I would strongly advise from getting into the truck.
Ad Hominem is grossly 'over-diagnosed' on the internet. I would say that the vast majority of the time that somebody claims somebody else is using ad hominems, what they are actually doing is merely insulting the other person.
In other words:
"You are wrong because of X, Y, and Z. You fucking idiot."
not:
"You are wrong, because you are a fucking idiot."
The first will typically get cries of "ad hominem", but it isn't. The second sentence is not being used to logically support the assertion in the first sentence, it is just a tacked on plain-old insult.
For example: A stranger rolls up in a truck up to a kid on their walk from school and says "get in my truck, your parents were in an accident, and I need to drive you to hospital". Now all the person said could be true - but I would strongly advise from getting into the truck.