I actually think "concealing the question" is not only a good idea, but a rather general and powerful idea that should be much more widely deployed (but often won't be, for what I consider "emotional reasons").

Example: You are probably already aware that almost any metric that you try to use to measure code quality can be easily gamed. One possible strategy is to choose a weighted mixture of metrics and conceal the weights. The weights can even change over time. Is it perfect? No. But it's at least correlated with code quality -- and it's not trivially gameable, which puts it above most individual public metrics.