I too had bad experiences in some of the meet up groups, specially the larger ones.When I joined I noticed they already formed tight sub groups and you couldn't squeeze in into one.They would give dirty looks ,if I introduced myself and tried to sit at their table.I thought I would be accepted after some time.But didn't happen.I still attended and was mocked at by a couple of women.I was isolated .I realized those groups were not for me.What is the point of being in a large group,if you are made to feel alone.I simply stopped going.If groups doesn't work for you,it is better to keep a couple of good ones.Those are enough I think.