I've heard all this before and till now have refrained from commenting but.....

I run a folk song weekend ....It is something I started because I wanted to get singers together....I do all the organising and correspondence. I put up my own money to make sure it happens and that everyone is happy and well looked after yet every year there are one or two people who try to tell me how the weekend should be run. Like Max, I'm very polite and ignore the comments but privately I am very irritated by what I consider to be appalling bad manners. Amazingly, these people expect to be invited back.
My feeling is that when I am invited to an event that they run then I may feel that I need to listen to what they are saying but one day I might just tell them to find somewhere else to go.