I think I checked out that 2-girls-1-cup some years ago, because everybody was referring to it. Now when I try to remember, I think it had absolutely nothing special? Did it?
I mean, of course, I've seen, owned and still own possibly 3 digit number of original scat publications (loop, mag, vhs, dvd) so I may be jaded. I think the most perverse scat I've seen, is the Kinky Thai stuff, which involves sharp and well shot close-up's of dog shitting straight into mouth of female. And 2 females in video share the dogshit, vomit and all the rest. I have hard time remembering do I actually have this anymore and if I do, where it could be.
But European producers like Manni Monto Prod are pretty much specialized in excrements and have thousands of releases. Same with Brazilian MFX. I do prefer something such as Subway / Kitkat club, since the scat action is usually combined to something. It isn't just lazy mess making, but rather girls with shit on their faces being ass fucked in some retarded nearly surreal scene.
I think the time of comissions is little bit over. In old days when there was less possibilities to find material, you would simply contact someone. Especially those with more obscure/artistic visions. Either for private use or he would make material and also publish it commerically. I remember series of Dutch hardcore s/m vhs, where fans would make equipment and send it to producer to use. Wanting to have slave with metal torture mask covering her head. Old school bondage artists a'la Willie, Klaw, Stanton etc always did material based on requests. Many of the Splosh! style mess makers or rubber fetishists got private material made by those small companies. Very specific budding & cakes thrown on clothes of female what will turn them on unlike some other budding, heh..
Nowadays, you whatever fetish you might have, you just type search and find it online. Already done, already available. You think of maybe I need book about female noses opened with hooks and cummed inside or such. And in old days you could say the local porn shop would tell you there's nothing they can offer. Now, well, there is a book about it already on commercial market and plenty of videos available just about everywhere, although pretty much japanese product.
I visited some days ago big 4-5 floor fetish porn store in Tokyo. Each floor was specialized in specific very narrow genre. Top floor was just sport fetish. Swimming, running, wrestling, dancing, gymnastics of all kinds, tennis, you name it, they got it. Floor below was all about superheroes. Women fucking dressed as superheroes. And thing went on like that. You could just imagine from top of your head some special type of DVD, what you may want to see (a'la girls dressed as superheroes crushing pastry and fucking rubberballs) and they'd have it already made and available for pretty heavy 60 euro pricetag. As a real DVD, not dvdr.