LOL! Thanks for the question Conservobabe. The answer is easy. I always hold the door. The woman's reaction tells me if she's a lady (they always smile & thank you).
Prompting gentlemanly behavior is almost the same as getting a puppy to wag its tail...you just pet them!
As well you should, if you are a gentleman. Tis nice if a lady says thank you with a smile. (I always do). But, a true gentleman does not care if the woman does not. He knows in his heart that he is who he is, confident in his definition of gallantry.