There are certain veiled codes or flags that are used in media of the 1930s and 1940s to indicate just this.

For an example you may have heard of in a film of the same era, Joel Cairo in "The Maltese Falcon" makes use of perfumed hankerchiefes.

There is another example in the same movie, where the young gunman in the same movie employed by Mr. Gutman isn't called a gunman, but is a 'gunsel' which is prison slang for a catamite.

::B::