That has been my experience as well. The usual schtick goes: anti-aborthanasia = Christian = illogical (or the leftist variant: anti-aborthanasia = Christian = The Man = oppressive). To argue in favor of life is therefore to relinquish all intellectual clout. It doesn't matter that this "argument" is based on cheap associations rather than actual reasoning - if you hold the supposed intellectual high ground you can just assume your assumptions are correct, and that any challenges are coming from intellectual inferiors and thus suspect, if not outright laughable.

I could mention a discussion I had involving X-Men and Dungeons & Dragons alignment, but just remembering it makes my head want to explode....