"I wouldn't like my daughter to marry one".
What, in the same way that your daughter shouldn't marry a stamp or antique collector? Probably an intellectual, possibly monied?
The interest is in the eye of the beholder whether its planes , trains, birds, stamps, coins, antiques, etc, etc. What the individual does about it is as varied as life itself. I started spotting in the early/mid-sixties. Nowadays I look for my pleasure, I'm selective about what I like and I note things that interest me. I'm sane (I think), solid and dependable (again, I think) and it has never been presented as an issue. Its far better, more comforting, and less anti-social than many things that people do!
RR