My first instinct when answering this lovely question was to ask, "What the hell is 'fat sex'." But, I think I know what "fat sex" is. It's having sex with a really fat person.
There is a major branch of pornography dedicated to those interested in "fat sex." It's categorized under helpful labels like: Plumpers, Chubby Mommies, Chunky Honeys and most notably BBW (Big Beautiful Women). So, right off the bat we can say: yup, some guys feel good about "fat sex."
What's more, one man's fat is another man's thick is another man's padding. Still, if we go to the extreme and talk about the unequivocally morbidly obese, there is still a population that thinks it's the cat's ass. In fact, next time you're at work, borrow your boss's computer and Google: Hot Fat Sex. You'll see.
If you are asking because you like having "fat sex," relax, you are obviously not alone. If you are a "fat" then worry not, there are plenty of folks out there that want to hump your voluminous body. A good friend of mine hates having sex with skinny women, but always forgets it; he's told me on more than one occasion: "Funny Guy, I don't know why I do it. It's like rolling around in bed with a bag of antlers." He is a perfect example of someone who'd rather sleep with the Woolly Mammoth type then the tusk type. And is he wrong?? Who among us hasn't sustained paper cuts from being sliced by a super model's hip bone during sex.
I should add that there are, of course, those among us who are anti "fat sex." These people are called New Yorkers. I kid. I kid. No, these people just like the Milan runway type, heroin chic or the ferociously malnourished type. To each his own. The bottom line: there's room for all types...of bottoms.