I tend to assume that if something is Flash-only, they just don't need me as a view/customer. I have Flash and animated gifs disabled by default. I do have the option of turning them on if I *really* need to see whatever they are, I suppose, but life is so much easier if I simply assume that "flash blocked here" part of the site just doesn't exist.

Occasionally I do, in fact, need something that's Flash-only. Generally I email or call instead, and I tend to offer a complaint about the Flash-only at the same time.