I agree, claims should be examined by themselves
Well that's encouraging.
It explains that an ad hominem isn't fallacious if the position the other has implicates their character/ motivations etc.
The only "problem" being that you can never know "their character" or "motivations" etc, due to your EPISTEMOLOGICAL LIMITS.
And even the most morally repulsive, malevolent person can still make a perfectly valid logically sound statement.
Their moral repulsiveness and malevolence do not magically invalidate their logic.
I admire your faith in sample-bias.
Please teach me to "Judge Correctly" without logic.