Anyone who thinks they can tell who is and isn't using by looking at someone should sell their knowledge to the IOC. Right now sporting bodies spend tens of millions for expensive and inconvenient blood tests, they'd pay many millions for a visual system that works.
Unfortunately none of the current visual systems works, which is why no sporting organization in the world uses them. But if someone has one that actually works they're going to be very rich. Especially one that works just by looking at a picture. Imagine, instead of chasing athletes down for blood tests they simply take a picture and send it to the genius Sherdogger who can tell if someone is using or not just by looking at a picture -- the person who comes up with a working visual system is going to be rich very quickly.
Me, I think everyone in the UFC is using, simply because it's too big of an advantage (especially in terms of being able to train longer) not to. But I don't pretend that I can tell by looking. I envy the soon to be filthy rich guy who can.