I also have the all white vegan leather seats and wear dark blue jeans just about ever day. I asked the Tesla tech, when he was our performing a minor repair to one of my door handles, what they used at the shop to clean the seats as mine had started to show a bit of dye transfer. He went back to the service car, grabbed a can of "foam glass cleaner" with a very conspicuously covered "3M" label and told me to give it a try (although per company policy, he could not recommend it over any other product as it was not Tesla branded). Sprayed a bit on a rag, then wiped a small spot on the seat ... pretty much good as new.
The 3M website claims the stuff is safe to use on vinyl, plastics, and just about any other surface and I haven't noticed any ill effects since trying it on a small spot. I'm definitely planning on picking some up and giving it a more thorough test. Will post pictures/results when I have some.