There are three issues in men’s swimwear: modesty, decency and safety. Modesty is tricky for men, because the parts women find attractive are not ususally covered anyway – it would be very hard to. The forearms, the neck, the back and the lower face are the places women tend to look when they’re sneaking looks at men (not nearly as much a problem as vice-versa but it exists from time to time). It wouldn’t be safe to swim with your neck, forearms and face loosely wrapped, nor could you go out into the store like that. But a top that covers the back would help. Of course, a very attractive man will find himself getting attention with his legs, stomach or chest visible, but as much from men as women.
Decency is a different story. Most men don’t look very good with their bellies exposed, and the same can be said of their calves, and other areas as well. Feet aren’t usually nice to look at either. So a good swimsuit for a man would cover the chest, belly and back, the area from navel to a quarter of the way down the thigh, and be loose enough to avoid clinging.
As for safety, there is water safety and there is sun safety. For water safety, the suit should not bunch or billow anywhere, and should not restrict movement. For sun safety, it should cover the entire shoulder and shade the upper half of the upper arm. I base this on where I see the most sunburns. So, I conclude that a perfect swimsuit for a man would be shorts looser than standard swim trunks but only a little bit looser, attached to a slightly loose muscle-shirt or stretch-sleeve T-shirt top with a mesh or other lightweight tank liner. A muscle shirt isn’t a tank top. It has straight-up-and-down armholes, so the shoulder is covered and they don’t cut into the muscle when you swim. That’s my:twocents: