This is the reason why I have no interest in meeting bands I like.
I have met hundreds of bands over the years (all of varying degrees of popularity). Some of the biggest names in the game were VERY cool (IE - Paul Stanley and Gene Simmons, believe it or not), as others were complete a-holes (not going there, so don't ask).
I for one have never met Lemmy. I have been a Motorhead fan since the mid-80s. It would KILL me if I met Lemmy and found him to be a a-hole in person.
Now everyone has their off days, so even one bad interaction shouldn't equate in totality the overall demeanor of the person, though it is that ONE interaction that will stay with you in your mind, ya know?
It's the music that matters and what makes me interested in these people / bands in the first place.