In the mid 1900's, men swam nude. Even at the YMCA, swimsuits were not allowed. They grew up thinking it was normal.
Some of them, however, I think are old perverts, especially if they just hand around for hours. I used to go to this gym, and this old guy would go work out for 10 minutes on a machines and hang around the lockers and steamroom for 3 hours. He would get in the steamroom, then go take a cold shower, and get in the steam room again. That isn't normal. Thats a guy looking for something.