After many years of taking potluck re whether the lady of my dreams was going to have nylons available on any given day, I've taken to buying and stocking nylons and bringing them along to trysts. It avoids the risk of disappointment.
Since I'm 6 foot tall and the girls are almost always a good deal smaller, I manage to avoid the sales assistants looking at me queerly at the checkout desk. I always make a point of saying: "I'm buying these for me girlfriend. She's 5'8" tall. (Or whatever). Do I have the right size?"
Of course getting the correct size for the girl can be difficult, particularly with those European brands which insist on measuring in cm. And some girls won't wear nylons at all because their legs are too slim and the hose won't stay up.
Problems, problems, problems....