We have actually eased the similarity criteria recently for images that have sales potential. It means we will accept more similars from a series of good images (i.e. nice authentic-looking models, in good light having fun in a contemporary setup/props, a niche-but-popular subject, etc.) than from the everyday shots (think common still lives).
Given that level 0 is applied after 6 months and that the images enter the database as level 1 files there is a faster price diversification for similar images. It doesn't mean we accept anything or that we don't expect photographers to do their own selection. Folks who simply dump their cards in the FTP folder are kindly asked to make a prior selection.
I know it's not the case for most of you and again, we keep in mind the quality of the submissions at review time. If your images are very good, salable, AR is high, you have better chances to have them accepted. If they are not, it's not the end of the world. See if you can improve something or move on.

Having said these, you are encouraged to ask for a second review using the form available in the Refused files section. A senior editor is reviewing those, someone different than initial reviewer. This comes as an additional support to the resubmit feature, who goes to the same editor. Both these assume the possibility that your refusal was unjust. Please take advantage of these opportunities and if the image is still refused, trust us and move on to the next images.

We are aware refusals are frustrating. You worked for those images, you spent time uploading and we spent time reviewing. We would much rather accept everything, but we have selection criteria we need to abide in order to keep our customers happy. The number of submissions is about 40% higher than last year. We could increase the size of our database dramatically but we prefer to remain focused on quality rather than quantity.

Thanks for your understanding.