Here's a subtle one... but I think it's pretty meaningful because it's the subtle body language / actions that make you know you pass.
Me and my roommate were talking on the phone, he was trying to get me to give him a ride somewhere when the call dropped. One of the last things he said was "We're going to a bar and they don't like girls there, especially girls like you because everybody else thinks you're a real girl." Well I went out and there was a guy standing there who my roommate was going to this bar with. After talking to him for a minute, he started to walk away. I was barefoot and I wasn't done talking to him, so I said "I'll follow you barefoot I don't care!!" His friend jumped in and said "Oh come on, don't make that girl walk like that barefoot!!"... I thanked him and shook his hand and he shook my hand very lightly like a man would shake any other girls hand.
He may or may not have caught that I'm trans by the phone calls, but usually my roommate mentions that he lives with a transsexual (well, two) when meeting somebody and bringing them over (which I kinda want him to do because I'm not so sure I pass 100% myself sometimes). However, I think his natural instinct when seeing me caused him to treat me like any other lady.
Subtle cues