Are men with long hair generally looked down on?

If he's a day labourer or self employed then no, not really. If it's my doctor or some other professional then yes, very much so.

I can see shoulder length. That was how he had it when we dated years ago. BUT this isn't the 60's is it!

If they tie it into a pony tail then yes.

I don't think so but I have a personal preference for men with long hair. Maybe because my father had very long hair when I was young and in general I'm probably not a good sample of the masses.
I have a real weakness to men with long hair.