What you call "Ghost Hunting" in that definition, I simply term as Paranormal Tourism. But that may be because I'm from a tourist state. (Florida)
I just want to be careful of using such terms as "Newbies" or devaluating the role of those just starting out. I just don't want to get into a situation where we divide into groups of those who have done this for years, and those who are not welcome. That I want to avoid, again because we all started out sometime. Also, one reason this site is here is to unite, not to divide. So although you're correct that training and caution is so very important, the very next step is to then provide that and be available to help.
As for spirits, human nature is human nature in life as well as beyond. You'll find good as well as bad, and as you said yourself those with intentions that are not so good will not come out and tell you "Stay away from me, I'm going to hurt you", but rather they will come as whatever it takes to gain your trust.
I think a great way to think of it is just as we teach our kids. Those new to paranormal investigation should approach it with the same restraint that we teach our kids. "Stranger Danger" just jumps to mind.
There are many who are hungry to learn, and rather than simply saying "Stay away", which we all know they probably won't do (few of us do, because of the draw to knowing the unknown), the best response is to educate openly.