I've been a member of my local guild for close to 15 years. While there are cliques, I have never been made to feel unwelcome. I've found that you have to get involved in order to get to know some of the people.
Our guild has monthly meetings with a range of speakers, from nationally known to local quilters. We also have BOM and charm square exchanges, a yearly challenge, community service projects, retreats, workshops, demonstrations, and (my favorite) show & tell. Every other year we hold a quilt show. Becoming involved in committees or activities allows me opportunities to work and become acquainted with members I might not otherwise get to know.
Of course, there are some who attend purely for their own entertainment and wouldn't dream of being friendly or helping someone else out. But the benefits I receive and friendships I make far outweigh any negativity.