I think you have come up with a great criteria for deciding when to be honest.

As someone who has lived a very honest life I can say with confidence, it doesn't work. It's made my life less happy, not more. I still do it out of habit, and also for the feeling of moral superiority I get, but if anything I am thinking about being less honest rather than more so. It just creates too many problems, especially if you are an entrepreneur or business person.