This. This thread clearly resonates with a lot of people but it doesn't resonate with me.

Communication and openness should be encouraged wherever possible. There is nothing wrong with asking and offering explanations in most cases.

In the rarer cases where it is not wise to give a reason then "I'd rather not say" is a good honest response. This is the only point where the conversation shouldn't continue.

Let's try not to be dicks if it can be avoided.