A recent friend request prompted me to blog about this subject today.
Perhaps I am just wary of adding people not vouched for after an incident in a private group with a friend getting harassed by some guy (same guy who sent me a message too, and he wasn't even unique about it apparently) and two others suddenly losing their accounts.
But for me when someone has only a few mutuals and isn't in any of my groups, nor does he appear to be an author, I just see danger.
After removing & blocking this particular offensive individual, I again had such a request shortly after. It smelled bad to me (maybe same guy created another account) so I decided this time to ask the five mutuals we shared.
In this particular case three of the other mutual friends replied promptly and said he randomly added them this morning and in the end I also realized he was underage anyway so uh, no, don't think so! Not good to allow underage people on your account! Moments ago I just had the last of the mutual friends confirm that he'd requested us all this morning. As another friend mentioned too, we wonder what list we're on!
My advice, and I believe it to be wise advice, is unless you know them or they are suggested by someone you know & trust I'd be aware of potential trouble.
In this business, with our content being purely adult, I see no reason to add someone who is underage that I don't know. Only twice have I made exceptions to this rule, one was for an aspiring author who was very honest about only being 17, whose birthday was a few months off, but who had asked me as a friend for the purpose of learning about writing. I was flattered at being asked to Mentor him and he has not disappointed me yet. He has always maintained an adult level of communication with me and several others I'd eventually suggested him to for learning purposes.
The other was also an author, but one I'd found who I wanted to publish and had parental consent to do so. He is a damn incredibly talented writer too!
So in a nutshell, please be very careful who you allow on your friends list or you too could find yourself the center of a very major negative issue from harassment to fb banning, none of us need that!
My theory: Not many mutuals, doesn't appear to be an author, not suggested by a trusted friend or have any common denominators or sends me an inappropriate pm... Any of these in my opinion equals a NO in the friendship request. Even then, be careful, if the above doesn't apply, not everyone is truly wanting to be a friend.
We authors have to watch out for each other too. If something seems off to you, take a minute and warn your friends that may be on his list too!
If it hadn't been for a friend letting me know what the first guy was doing (my busy schedule had kept me from the group that day) then I may not have known he was up to no good until it was too late.
Take care, stay safe and keep on writing!