I generally think of everyone as the same until they give me a reason to consider them either good or bad.
Examples of bad would be screaming movie catch phrases in situations that don't call for it, bullshitting to try and improve their social standing, not taking hits, being cocky arseholes and similar.
The people who are new to it and act in a way to give me a negative opinion of them, I rarely see again. They come along, act like an arse, get the vibe they're not wanted and then don't come back. It's their fault for not being more pro-active, they don't help themselves by pretending to know everything.
On the other end of the scale there are those who actively seek help and advice, the ones that go around the safe zone chatting to people, asking about kit, asking what to do and where to go on the field and offering their input when it comes to planning an attack. Those people I willingly help and step in to assist them in any way I can when others shun them for being so upbeat and positive.
I'm not talking about kids here, they could be 12 or 112. Age to me is no concern, young and old come with their own traits, they can cross over, you can meet older guys in their 40s who you could mistake as 15 year olds if it weren't for their grey hairs and wrinkled grins.
Once at my regular site there was a bloke who'd come for his daughter's boyfriends birthday party, there were about five 15yo's with him, he must've been about 40 and he was honestly one of the best guys ever. He was brand new, no idea what he was doing, what was happening, but he shadowed me most of the day, asking me where the best spots were, where to lay down fire, where to keep an eye on, how to move around safely and everything. Common sense questions and a positive, willingness to be helped.
We had a right laugh, it was great. If every new player was like that guy, I'd be the happiest person in the sport.