There are a couple of key phrases here:

-’likely’ to be enjoyable — what kind of probabilities are we looking for here? And, don’t we have reason to believe that people are not so good at accurately assesing the probability of their favored outcome?

-’enough’ joy — how much joy is enough to outweigh any additional long-term happiness one might gain by changing course in the light of bad news? And, don’t we have reason to believe that people are not good at weighing future joy vs. present joy?

So how does the math work here? If we don’t know how probable someone’s future joy is, and we don’t know how much future joy can be gained from responding to bad news, and we can’t accurately compare future joy with present joy, how does this calculation work? This is why most (by which I mean ‘all’) people develop truth rules to guide them: ‘Always spare my wife’s vanity when she asks if she looks fat’ is an example of a truth rule. These rules seem to be based on some form of collective calculation about the harms and benefits of certain kinds of ‘bad news’, but interestingly, people are mostly expected to abide by them (and be polite) whether or not their calculations lead to the same policy.

That said, your post doesn’t seem to say much more than that if a man’s wife asks him if that dress makes her look fat, and it does, he shouldn’t say “Yes”.

I don’t buy it.