Just came across this thread after finding some of my images on barewalls.com.
They have 165 images of mine and they do have the cps_ prefix for my name.
So I checked Can Stock Photo and I do have exactly the same number of images on there, so there is a direct tie in.
However when I search the barewalls site for images of a particular location and then look at the best selling images, several of them are mine.
When I look on Can Stock, it shows no sales at all for those images.
Either I'm being diddled out of sales, or barewalls "best selling images" is just a lie to boost sales.