interesting ways of getting at the truth

I just wanted to bring together a few ideas I've encountered under the heading "interesting ways of getting at the truth".

Idea 1: bayesian truth serum — ask people not only what they think, but also what they think other people will think. Allows people to express a minority opinion while also demonstrating that they are aware that their opinion is in the minority.

Idea 2: list experiment — ask people how many items in a list they agree with, but not which items they agree with, where half the people see a list with a socially objectionable thing added to it, and half don't. Allows each individual plausible deniability about agreeing with the socially objectionable thing, while still revealing what percent of the group agrees.

Idea 3: wine tasting — have someone write a yes/no question about some wine, and then have two groups answer the question, where one group gets to taste the wine, and the other doesn't. If the group that gets to taste the wine can answer it better than the group that doesn't, then the question is, in some sense, legitimate.