This rules out religion, politics, philosophy and most policy proposals as interesting controversies, leaving scientific and epistemological questions.

Slightly problematic unless you don't admit epistemology being part of philosophy. And it seems like almost as big a swamp as the rest of philosophy, though the problems seem much more worth resolving than in most of philosophy.

There is a paper "Experts: Which ones should you trust" addressing this issue by Alvin Goldman (http://philpapers.org/rec/GOLEWO -- you need JSTOR or something to actually get the article), one of the biggest names in epistemology and specifically social epistemology. Actually I don't think the article does very much to resolve the issue unfortunately. By the way, there are two schools of thought self-described as social epistemology which don't acknowledge each other except mostly to trade deprecations. Actually I don't think the article does very much to resolve the issue unfortunately.