I know this is an old thread, but I agree with some of the points made here. Although I'm a man, "lady/ladies" makes me cringe in some situations. As members have said, it depends on context.
BettySwollocksandaCrustyRack, "lady" isn't even the equivalent to "guy" or "dude". Both those terms are slangy, informal Americanisms and not polite or respectful terms in the way "lady" is, the counterpart of "lady" is "gentleman".
I also notice how "lady" is used much more than "gentleman" and "gentleman" is often only used in certain situations or in its proper sense, ie. "he's a real gentleman".
I can't see anything wrong with "lady" being used politely in situations where a man is called a "gentleman", ie:
ladies and gentlemen
This lady/gentleman has an appointment with...
But I cringe when I hear someone being called "young lady" or someone using the word loosely where "woman" would be more appropriate. Men or boys would be addressed as "young man" and never "young gentleman". I noticed how some people find "woman" rude in certain contexts, but not as many people seem to find saying "man" as rude.