KBaker, my boss is 55 and he was saying the same about being invisible to young women a few days ago. In his words, "If you put me in a room with twenty 18 year-old girls, shut the door, came back in an hour and then asked if there was a man in the room, all the girls would say no".
Jesus H. Christ! Now, that's bad.
Anyway, you're only invisible if you don't have what they want. If you have fame, notoriety, or money, you can be visible no matter how old you are.
At 39 I don't consider myself invisible to young girls, although I know they look at me with disgust. I guess that's better than nothing. he he