For most kinds of persuasive argumentation, especially in complicated and emotionally laden subjects like child rearing, arguments work on us without us ever being able to fully evaluate their merit. And in that world, it does make sense to down-weight arguments that have some bias built into them.

When we are dealing in such topics, we presumably have our own bias on the subject, and in making some assessment of the degree to which another's argument might need discounting due to their bias, we may bring our own bias into play. Are we then risking just ignoring people (at least to a degree) because they disagree with us?

I'd like to turn the question back on itself here, should we distrust your argument that allows us to discount arguments, especially in emotive debates, on the grounds its conclusion is possibly self-serving for you? that it excuses your discounting of people you disagree with in emotive arguments?