Younger women and older men
You're both right and both wrong, DrZ and TooCold.
There are some women who like, and even prefer men who are older than them -- especially for FB situations -- and some women who are absolutely dead-set against going out with men over a certain age (which might even be only a few years older than them), even if the guy looks younger than they do. It's not "one size fits all."
I tend to go out with women who are considerably younger than me because: 1) I'm not in a particularly stable and settled-down life situation, and, much more importantly, 2) I look a great deal younger than I am. I've even had women who are younger than I am reject me by telling me i'm "just a kid." Flattering, but annoying.
Online dating is not the place for people to find others who are of a much different age than they are: the numbers are just about everything in the online world, at least as far as getting off the starting line goes. Most of the women I've dated in real life would not have even considered me had we made our first contact online. So a fellow a women might think "hot" metting him in person could very well be seen as a "creepy old man" online if he doesn't conceal his age. That's just the way the game is played.
When I've had a go at the online thing (with and amazingly high % of replies, but nothing more than a few dates after that), I've rarely written to women whose "laundry list" I didn't fit 100%... yet I have had a quite few women write me who had criteria stated in their profile that my profile clearly stated I did not match. Go figure ... chick logic.
************
I would expect a large % of not too hot or ridiculously selective (guilty as charged, in my case) people (of both sexes) on dating sites. Who are most likely to be available, after all?