They are stereotyped to some extent, but the total look matters. A guy in jeans and a flannel shirt with a ponytail is a completely different stereotype from a guy in a suit with a ponytail. I think to some extent when a man decides to grow long hair he is probably embracing his perception of that stereotype. The ponytail is a marker of how he wants to be seen, and he will likely be seen that way. It’s just that what he sees as a positive association, many others may see as a negative one. And yes, age matters. Sometime in a man’s thirties he starts to look a little foolish and desperate with long hair. I say this as someone who had long hair for a very long time an swore I would never get rid of it. I cut it all off just before my 30th birthday.