Years ago I submitted two selections - a range of things that weren't as "stocky" as most of my stuff. They rejected them all - at the time they didn't give any reasons. I stopped submitting as I had no reason to repeat the experiments without some further idea of what they were after.
To their credit, a few weeks later they contacted me to see how I was faring as a new member of the site. I replied about the two trial batches and no idea of what their wishes or criteria were and that it seemed not to make any sense to upload more. Never heard back.
I've never heard anyone boast of great sales there - so they could be and folks keep quiet about it, or they could just be very niche and very small. They've been around for a long time though, so they're obviously selling to someone