The consensus in the trans community is to let a potential partner know earlier, rather than later. It avoids the situation you've encountered. Some men also can react violently, when they find out, so it's quite a critical dilemma to them.

Unfortunately, not all follow that mindset. They also tend to bust out a lot, and so lead a lot of men on.

It's a bit like the scumbag dilemma women face. Very few men are scumbags, yet women encounter them regularly when dating. Most men try not to annoy the women they find attractive. They are careful in their approach mentality. This means they only make a few approaches (relatively). They also tend to pair off, and so exit the pool. Scumbags cast a wide net, and don't hang on to women for long. This means they make a LOT of approaches, and so annoy a vastly disproportionate number of women.

Basically most trans people try to be as polite and careful about it as possible. A few, unfortunately, can destroy the reputation of the rest by being scumbags about it, at least locally.