Not true as far as I have seen. I had a blue roo that I sold. He had the worst case of pasty butt and had it for two months it seemed. Before I sold him, I loaned him to a friend who now has 3 nice rumpless tufted chicks from that roo. Since it was the only roo with the girls, I am assuming they are his. I don't get alot of pasty butt here, maybe 1 chick out of 10 or so. The roo was special because he loved baths and blow dries. He would come running when I would say bath, then he would sink into the water and close his eyes. Same for the blow drier. He would lean into the air and close his eyes.
Any hoo, I have not noticed a fertility issue with pasty butt, maybe others have. Now sometimes the birds that seems to have pasty butt, actually have fluffy butt and the poop gets caught in the fluff and starts to look like pasty butt. Fluffy butt does cause fertility problems, so you have to trim the fanny every spring and your good to go.
Lanae