As a frequent reader but very infrequent poster on this forum, I have considered this post carefully, having followed the thread with interest.
I've been riding with various clubs for over twenty years (not fickle, work has made me move clubs) and I can honestly say I don't recognise this sort of behaviour at all in the clubs that I have belonged to. I've raced in most disciplines, but overwhelmingly ride my bike for pure enjoyment, and have done many thousands of miles to and from work. I've ridden on club runs and chain gangs many times and there are expectations and standards of behaviour that are almost fiercely guarded and preserved. They don't include being arsey to anyone.
Similarly I have never experienced it from groups from other clubs that have caught me (frequently) or that I have caught (infrequently). A welcome smile, 'sit in for a minute' or 'interesting bike' have been my recent experiences when I've come across Southdown Velo, Fareham Wheelers, Lewes Wanderers and others. And I knew they were lying when they called my bike interesting.
The most anti social, chest puffing and sometimes downright rude and dangerous riders that I've encountered are those on carbon Treks with Zipp wheels and £200 Sidis when they're out for a 5 mile 'training ride' before loading the bike on the back of the 4X4.
Club life has a lot to commend it, particularly some of the more forward thinking clubs that recognise any sport can only survive by bringing in new blood.
I'm sorry if some of you have had bad experiences with club riders - I'm certainly not saying it never happens, but the vast majority of club members are true cyclists who love the sport and the passtime of cycling, and would be appalled if they saw this sort of thing happen.