I raise them (Seramas--in quality, show quality in some if Im lucky that year, and they are from Malaysia originally..do I call them Malaysian, although I prefer American Seramas ) .............and I have never crossed them with another breed. My birds are size and type up to the SCNA Serama standard. Im in a lot of groups with EDUCATED serious Serama breeders and none of them cross breed.
I HAVE seen people that get Serama thinking they will make a ton of money and they dont do the research, and get junk or cross bred breeders and breed more junk. They dont even know what Seramas are suppose to look like. I dont want to name names, as I think some of the "breeders" are on here, but I know of some sites where you can see these crosses.
The main thing is...do your research and educate yourself on breeds and breed types, and then you will be able to see a huge difference.
If you want real Serama, know what you are looking for in a great bird and ask for pictures, and weights. Ask the breeder for good and bad qualities of each bird.
DO be careful of birds that are "show quality"...to me that means you can buy it and put it in a Show. Some people say that if the bird comes from stock that produced a show bird. Other people might just say that. Do your research and know what you are looking for in a SQ bird, and get it from a reputable breeder.