First of all let me say that Dreamstimes strict acceptance criteria definitely shows in the quality of stock on this site. Bravo!
Now that is out of the way, let me share a tip with you to help with acceptance of your rejected submissions.
I'm sure everyone has had this type of rejection before:
"This image is overfiltered. Its use for the potential designers is limited because of this, therefore the image is disqualified as a RF stock-oriented image. Please upload the original instead."
This is especially easy to get if your doing night photography which automatically gives you more saturated colours ("over filterer look") during long exposures or when your shooting skies with a polarizer.
So before you start from scratch and throw all you post-processing work down the drain (i.e. levels, noise reduction, sharpening, contrast balancing, etc.) try this simple processing technique.
I use photoshop but I'm sure other programs can do this also.
What you do is make a new blank layer on top of rejected photo. Fill with black colour. And than adjust the opacity of the black layer until the colours don't look so saturated or "overfiltered" This works for me many times. Be careful about whites though. It may make things look a bit gray. So you can mask out those areas. The two photos in this blog were first rejected but with the following technique, they were accepted.
I hope this helps with your acceptance ratios. Cheers. :)