Are you under the notion that all trans people are easily distinguishable at a glance?? Many of them are not. At all. "I went on some dates and later discovered they are trans" isn't some imagined scenario. That's very real. People have
murdered trans people when they got involved with them and later discovered they were trans. (Example:
https://en.wikipedia.org/wiki/Murder_of_Gwen_Araujo). People have filed rape charges against a transgender person because they were intimate together and LATER discovered the person was transgender.
Here are some examples of transgender people:
Good grief. I know totally cisgendered women who have no problem being identified as "she" and getting hit on by guys until they put on some bulky clothes and suddenly get called "he" and get flirted with by women. I've known one cisgendered guy who got misidentified as a "she" and hit on by guys way more than he was comfortable with.