Do you mean evidence as to whether people with lower credit are likely to do such things against the company's interest? If so, I'm not sure. I just know it's something that is considered for govt purposes re: security clearances and that logic seems to carry over to private sector.

Before I or others go looking for such, what would you consider an acceptable standard of direct evidence?

I honestly don't have an opinion on it. It just seems something that's repeated and accepted often and I'm being skeptical is all.

I will probably look into it myself too! So whatever you can add to the discussion is great :)