T
I had a skateboarder backtrack after seeing me and say, "hey, is there any way I can try that?" After talking to him for a couple minutes I gave him a quick tutorial and he did very well. Once I told him how fast it can go, he got a little nervous and slowed down.
I say, just use your best judgement. I like to talk to people first. Just casually introduce myself, get their name. Just a little info about them. A lot of people just want to take a picture or video. Generally very positive response!
I did let my good friend on it and he spilled pretty hard without any gear on, leaving him with a little road rash.
I wont let kids under 13 try it.