but I'm curious how you arrived at "racist" as the sin which taints by association, rather than, say, "short-sighted" or "libertarian" or whatever.

Because calling someone "racist" tends to be perceived as implying that they're not just mistaken but morally deficient if not out right evil. Something that's less true for "short-sighted" or "libertarian".

It's non-obvious how saying "'No more bailouts' is racist!" might be defended.

Something like this:

• Some of the bailout money went to help blacks.
• Therefore, the people arguing against more bailouts want to hurt blacks.
• Therefore, they're racist.

Note, the above argument is by no means the most absurd argument I've seen for why something is racist.