Those that for one reason or another... only "dress" partially and leave home and go about their business that way. [giving CDers of all varieties a "bad name or image" according to some of the herd that water here]
It's fairly easy to guess, that many here do so, but are more than happy to usually just read threads.
Since many here are always asking WHY would any man do such a thing, here are a few possible answers that are kicked about from time to time that might speak to you or feel free to throw more in.
1] I could never "pass" in a million years, so I am not going to bother. [with wigs, makeup etc.]
2] I just like the clothes and/or I have NO need/desire to pass as a woman.
3] I am trying to start a new fashion trend.
4] I don't care what people think or worry if they will approve or not.
5] I realize there IS NO WAY TO TELL whether one passed or not, so why bother spending hours trying.
6] ???