They are real, but they are nothing special. On that
page that was linked to earlier, about a quarter of the way down the page; look at the one with the leaves. That is run-of-the-mill droop/sag right there. Bad shape, weird gap in the cleavage; and, they are not even particularly big. I don't care for her face or 80's tan either, but that is beside the point.
For a nice face and amazing natural breasts, do a Google search for the Danish/Swedish porn chick by the name of Aya Nielsen. For the bigger-is-better crowd, for massive size (natural) with good shape, look for:
Yulia Nova
Maria Swan (aka: Princessa)
"Busty Merilyn" (no last name I guess?)
Lindsey Dawn McKenzie (of course)
Not all of the above women have much for a face, and LDM is a bit on the "sturdy" side but for sheer natural size and shape on a decent (and in some cases, excellent) body, these are the best I have seen on the net.
Yulia Nova has gotten harder to find since her sole photographer made a big legal issue of other people posting her pictures on their sites; but there are still pictures of her out there I'm sure.