I don't think I'm that big, but that may be relatively to my size, my dick doesn't seem that big to me. With that said, I've been told, witnessed how people have to take me very slowly (at first), and I eventually measured so I realize I'm bigger than average. When I look at my privates (without a comparison)... i don't look that big in my eyes (the same with my hands).
I haven't, thankfully, been told directly, "I won't bottom for you." Although I did have one guy say he would but never did when we would meet up. I think he was scared/worried I'd hurt him, but he never vocalized it.