I can't help noticing that some of these meetings were when the celeb was on duty (signing, official meets, performing etc) whereas others were spotted in the street, met whilst fm was at work, whatever.
Perhaps some of those who seemed nice in the former circs might be absolute horrors if met in the second. You'd have to be an idiot not to put on a smiling face when scheduled to meet your fans.
The horrors always come across as the most interesting in my opinion. Although I suppose I mightn't feel that way if I was the one doing the meeting.....
I haven't met anyone famous myself.
I see what you mean. I would actually not approach a celeb if I saw them going down the road or trying to do their shopping, or all that sort of normal stuff. They are "off duty" then and owe nothing to anyone, and, I think that should be remembered and respected.
Of course, nothing is foolproof. I've read of plently of people who have had bad experiences at organized conventions and premieres so just because it's an organized event that doesn't mean you shouldn't be prepared for anything.
Celebs are real people who have good and bad days and, like real people, some are nice and some are not. You just have to go with it and if you have a bad experience, it's a shame, but it's how people can be - all people.