I have to admit you're right about the way people assume and judge those people with disabilities that can't easily be 'seen' it's not fair but our society seems to still place so much weight on appearances, it's just the way it is still unfortunately. I definitley feel for you KennyJack, I don't get that kind of judgements thankfully but I do get a lot of:
"Wow you get around really well, how do you do it?" or "My hat's off to you darlin' you are amazing..."
That is from total strangers when I go out into the world, usually I can see others looking at me getting around with admiration. I always tell the clerks when they ask, "Do you want help out with this?" I reply, "Nope, I got it down to a science, I am my own shopping cart." And then I take the bags and load up my lap holding the handles in one hand and using the other one and my foot I navigate to my car, sometimes it's awkward but I feel empowered to do this and proud I still can, you know?
It's not easy being disabled, and I have found that you should enjoy what things you still can DO and not dwell on the things you can't. That just leaves you feeling empty and bad inside. I'm sorry people treat you that way KennyJack, but at least you can talk about it here and people here won't treat you that way.
If you need to vent we're here for that too.