On DeviantArt it apparently was WhiteDove: http://www.equestriadaily.com/2012/05/hasbro-sends-cease-and-desist-to.html
It is a difficult topic really, while it is clear from a law perspective =/. Thing is, that the guy from FNAF could do something about it and I always wonder if that is worth the possible hassle.

You are right that it happens often, though. Some sell art-CDs with MLP-Porn and I am not sure how some would like it to have a trademark infringement for selling porn in their criminal record. As the US-Law demands it a company _has_ to make a move once they get informed about their trademark being infringed and some asshat could tip them off to ruin another fur's day.

If you think about it and then see how many people on the fandom render themselves vulnerable this way, I am not sure if it is not better to make people aware about the dangers involved.

I don't think anything will happen because of FNAF-merchandise, but what I think or what others do is meaningless, sadly.

Ah man that does suck for whitedove. Someone must have had a beef with them for some reason to contact Hasbro about it. There are other pony plushie artist though that are doing beanie baby style, shoulder rider plushies, little chibi styles, mlp hats, loafies, ect. Hasbro did come out with a multitude of pony plushies I believe recently that are more upscale and towards the specific pattern of whitedoves but not as big. It's probably why I've seen them pop up now in comic shops. (Edit: haha I found it~ http://www.toywiz.com/4thdimensionprincesslunaponyplush.html <-- Luna plushie link) (editnumber2: I also found that whitedove is still an active pony plushie maker.)

Good thing I don't sell porn. It's kinda weird that the porn fanartists that do it on commissions and cd's as well as those adult plushies dont get told on while the clean plushie makers do.

He probably can do something about it but really hasn't said anything on it. And might rather go after the people that are well known at making the plush toys that make hundreds on a single plushie alone (just a theory if it does happen). I know a lot of people don't do homestuck stuff (specifically the horns) because the creator has specifically said not to.

I think everyone does know the dangers involved in making things that could easily be seen as 'bootlegs' to official items of the trademark. But I do believe in differences from blatantly copying off of things (making it look like from the show/game/movie such as remaking the Fnaf dolls that were rendered in game) to making a folk variant. But alas I do think it comes with the hazard of being a FanArt artist (partial fanart artist in my case). Since I do know a lot of cons actually do follow the artist booth rules that it has to be 50/50 fanart and original things but the fanart has to be your own creations not redraws of screenshots,traces,ect.