If someone holds a door open for me because I’m just a couple of steps behind them, I appreciate it. If someone holds a door open for me because I have tits, it pisses me off.
However, I try not to make assumptions about why people are doing these little chivalrous things because it also pisses me off when the visibly handicapped give me an attitude for lending a hand in such ways. I’m not holding the door for you just because you’re using a cane or whatever; I’m doing it because you’re a fellow human being and I’m nice, fucker.
Fun story:
Once, I held a door open for a guy who was probably about twice my age (I was in my early 20s) and he looked completely shocked. “I’ve never had a lady hold a door for me before!” he said. I laughed and told him, “Well, you still haven’t.” His thoroughly confused look made my day.