Are you discussing the Miller or Gottfredson case? I think the fact that I know of two cases of people dealing with really severe difficulties in getting tenure by osmosis, without seeking them out speaks to their commonness.

I think we may be speaking at cross purposes. I care about this because ideological diversity leads to a greater diversity of viewpoints, which makes it more likely that the hypothesis will be examined from a number of viewpoints, so any flaws are more likely to be discovered. This is a social psychology result that has held up to replication.

What do you mean by negative outcomes for conservatives? I would have thought that denying one tenure for one's political opinions would be a pretty negative outcome for any academic.