A co-worker of mine had a good idea: require management to seal within an envelope the cutoff value that would determine the outcome the decision that required

A co-worker of mine had a good idea: require management to seal within an envelope the cutoff value that would determine the outcome the decision that required the estimate (e.g. Estimate > X then Do A and Estimate < X then Do B). When the estimate comes back open the envelope. So often, management wants a certain outcome, but needs the estimates as cover for making the decision. Just demand a detailed estimate, fool around with the estimates details--no matter what the estimate ends up being, and finally say "Estimates indicate that we should do this.", which is what they wanted to say all along.