My experience has not been all that great, because I don't want to be "that guy" who imposes on anyone else.
I grew up as an only child, and because I skipped grades in elementary school, I had no real peer group. As a result, I became pretty much a loner. I'm the kind of guy who can go someplace where there are lots of people, and no one will even notice I was there.
Somewhere along the way, I developed this attitude that if people wanted me to be involved, they would make the effort to include me . I didn't take into account that everyone else is pretty much self-centered, and expects others to do all the work. So I blend into the background, and rarely, if ever, get noticed and almost never get included because of it.
I tend to default to the position that my interests and desire to communicate becomes a burden on people, and that they all don't really want to hear from me. If they did, they'd be the one to get in touch. So I don't initiate conversation or communication very often, because I don't want to impose myself on anyone, which in turn seems to put a stop to any communications. It's a vicious cycle. I've somehow convinced myself that if someone really wanted to talk to me, they would make the effort. So I don't have much contact with people. I feel like they have to be the one to start something, because that's the only way I'll really and truly know they're doing it because they wanted to, and not because I asked. Oh, I suppose I could always think "well, if they didn't want to they'd never respond" but that's not the same thing.
So I don't have much experience with people "flaking" on me, because I rarely get invited to be in on anything. Sad, isn't it?