It can be tempting, during an argument, to attack people who disagree with you, but people aren’t necessarily wrong simply because they have flaws. Name-calling and insults are not one of Aristotle’s rhetorical appeals for a good reason and should be reserved for elementary-school playgrounds and presidential Twitter accounts.
There is a place in arguments for pointing out problems with sources, but that’s not the same thing as base insults. A source of evidence may be biased, fraudulent, or otherwise suspect due to a checkered past or dubious credentials and these things should be pointed out, but you can’t discredit a source just because you dislike like them or dislike something about them.
