We only curate photos from CC0 resources. For both curated and user submitted images, we verify the identity of each author and perform reverse image lookups for each photo to ensure they're not copyrighted.
We always do a quick search and cross reference the email, author name, and theme info to make sure everything matches up. It's usually pretty easy to sniff out when someone uploads a theme that isn't theirs.
We wrote a blog post on great places to get free stock photos and shared it on StumbleUpon. We ended up getting 17,000 visits that day and it just went crazy somehow, even though our domain rank was non-existent. We were getting 10,000+ visits for about a week because of that blog post.
After the dust settled a bit on that post we were getting over 1,000 visits a day (still a lot from StumbleUpon) and now we're creeping over over 2,000 a day and slowly climbing.
Obviously, a lot of that traffic was not highly targeted but it still gave us a huge boost and our Google rankings have shot up lately. We're now on Page 3/4 for "Bootstrap themes" and getting more organic traffic which is great.
Unlike most marketplaces, we're offering high payments for authors who don't sell exclusively with us. We're seeing a lot of high-quality theme shops opening up who want the option to sell on their own platforms but still utilize marketplaces for additional exposure.
While wrap has done a great job building up a user base and getting first mover advantage, we're always reading complaints on social media and forums that their support is lacking and that the site has not been updated. We wanted to give designers a better option and give great support to both buyers and sellers. Once we increase our sales and following, I'm confident that authors will want to switch over. Right now we're on page 3/4 of Google hoping to move up to page 1 very soon.
Our goal is to grow a great community around the marketplace. We've already started doing this with our blog and tutorials. We will be adding more features in the near future.