The request for a photo of each item is the best way to stop fraudulent activity in our opinion. As a buyer of over 800 LEGO sets, displays, minifigures, etc... on eBay, I can tell you that I look for actual seller photos when buying or bidding on an item, unless the seller feedback is exceptional. Since we don't have any seller feedback yet, the real photos will help weed the jerks out. That being said, here's what we expect:
For minifigures or small sets that people have mass quantities of...Take a picture of the whole lot of items to show that you actually own them. An individual picture of the box/polybag would be nice as well, but I don't expect you to take a 100 separate pictures of a Series 5 CMF for example.
For larger sets, I would suggest separate listings, unless all the boxes are similar in condition. Even then, you should show buyers a picture of all the sets to build confidence in your listing. Obviously, the more expensive the set, the better the pictures and description should be.
Over time, when people begin to build enough feedback and the site matures, we will bend the rules for great sellers. We are just starting out and the photo request is a good way to stop fraud.
I want members to realize we are going to give people ample opportunity to sell their sets for free or dirt cheap fees. All we ask is that people put some effort into their listings so we can give others a good idea what the site is capable of.