Is a sun tan never healthy?

Mixed results: The skin tans to provide a protection against the sun, and your body makes the tan as a protectant. We now live long enough that the side effects: skin changes and skin cancers have time to develop. Best to use sunscreens if possible.

No, except maybe in a couple of rare situations that should not happen in today's world. If a person has no choice but to stay outside in the sun, has no access to sunscreen, and lacks adequate clothing, then it would be better to be tanned than pale. If a person has no sources of vitamin D at all in foods or supplements, then getting sunshine could be better than suffering vitamin D deficiency.