With all the discussions about it, I tried the effect of both.
On the first pic the left shoe is treated with Jason Markk, the right is untreated:
As you can see, it cleaned the white portion quite good.
Then I threw both in the washing machine, here they are after:
Jason Markk is good, but expensive and mostly overrated.
Just throw the shoes in the washing machine to get often better results.
Also they are cleaned through and through, not just cleaned for show.
It’s like comparing brushing teeth to showering.
What gets you cleaner?