Most men do prefer slimmer ladies, that is why brothels don't take on BBWs.
That's because they generally believe the stereotypical image of a prostitute, and wouldn't know how to market the larger/older ladies. Well, actually they would probably promise a size 8 20 year old latino, and in the room you'll find a size 16 40 year old Romanian.
I've been offered work in a brothel. I've been asked to join agencies. But I went with neither, as they wouldn't know how to advertise ME