Yeah well my canon has all different art styles as breeds. Some are in affiliation with Hasbio and some are simply third party companies cashing in on a trend. People tend to not like McGonagall or Artist-kun breeds because they tend to be hellgremlins and smarties. They’re marketed as pets but are actually more feral than domestic. The Moonie fluffies are a recent up and comer and have a landslide of success with releasing Mystic and her mummah’s brood of Gen 6 fluffy ponies. Everyone wants a Mystic in their life. Carpdime, Quickhorn, Spoosh, fiddwe and Buwwito fluffies are also quite popular in my world because of their docile, sweet and loving nature. Wolfram fluffies are a mixed bag. Some find them needy and whiny and others think they’re alright. The only people who enjoy Shafer fluffs in my work are abusers.
So yeah, sometimes a fluffy pony is another art style breed and thats why they tend to look different from piece to piece and sometimes I imagine the scene or pony drawn in that particular art style or I just wanna pay homage to the artist. Like with Wendy, my pregnant foal. She’s not really an OtherOtherCoraline fluff, I just drew her that way because Coraline’s soon mummah drawings are the cutest. And we alll know I LOVE mares and soon mummahs.
And yeah, mc g’s fluffs always had poop encrusted on their asses domestic or not. 
And the butt-hooves,. Never forget the butt shaped hoofies.