Well Mayra, good question, but
I'm not transitioning yet, and if I was to do the full monty and was to not tuck at some times, I would choose my clothes VERY carefully. Very, very, carefully.
I remember a female teacher I had in college ten years ago. She had short hair, tight jeans, and very often, a very disturbing side bulge, which to my opinion, was very much intended. Yet, she was not FtM. For an MtF individual, the effect would very much be the same, I would think it would be intentional. And I wouldn't understand why, in this case.
I want to say that if you even with a distracted look on people walking, you can see the presence of a "suspect" bulge or not. Even if you don't specifically pay attention to it.