Oh NotSpaghetti, I didn't think you were! I should have said that of course there are irritating people in all walks of life - and some of them end up volunteering!
I rather assumed that the original post was about the kind of people who like sneering, probably because of my own point of view.
My own pet hate is women who think it amusing to tell you that they were 'thrown out of Brownies' followed by a silly anecdote about how petty 'Brown Owl was (often to do with knickers, just to make it funnier).
I have no problem if someone didn't like Brownies - but as an adult please recognise my mum's contribution:
She would come home from a day's work, that would often include a stop to check on her frail parents. She would get everything ready, walk with us down to the Hall, where we would help set up activities. She would join in weekend workshops and keep herself up to date and plan sessions. She was thoughtful to those who had difficulty affording uniform or subs and made sure they could come on outings. Long before 'inclusion'she welcomed girls with disabilities and planned for them to be welcomed and able to take part. She did that for an entire generation. Her only, but best reward was to be cared for at the end of her life by nurses and carers who had been her Brownies, and their singing of campfire songs at her funeral is one of my best memories.
Of course, such service doesn't make an amusing anecdote!
Wicked Little Letters? (funny film of a long-forgotten case)