All hybrids. Nothing pure at all, neither SW nor WD (not that I care if a stingray is pure or not... but some people do).
Also, a big factor for those super huge insanely white spots is the way they are kept. In completely white and bright tanks. Put them - any SW or WD for that matter - in a dark tank, perhaps in a fully blacked out tank and you can literally watch the spots shrink slowly but surely.
Personally, I like their looks but I'd never ever buy one because I just simply do not want to keep them in a WTT (White Tank Treatment) as I find it ugly and I'm not gonna spend a sh*t load of money on a nice ray when I know he's gonna get uglier in a more naturalistic looking tank.
Animals, including rays, try to find ways to "camouflage" with their surroundings. Meaning, in a completely white and extremely bright tank, they'll give their best to get extremely white & bright. In a darker setup, they'll get darker. It's quite simple. Not that long ago, I have bought a pair of HET pearls. They were insanely bright in colour... not even 2 months later, they turned very dark in my setup (way darker than at the breeder's place).
What I find the worst is that some of those mega big spot rays, especially the breeders' mascots, are literally getting stunted by their owners because growing them at a normal rate would very likely (like almost 100% certainly) mean they'd get more black than white. But oh well, thats a completely new topic.