When it comes to surplus loads, there are definitely better suppliers than others in regards to how they break their loads down for sale. Of course choosing the right type of loads is also important, for example you'll most likely find more issues with customer returns than you will in a new overstocks load.
If you're really lucky you may even find master cased goods, top shelf stuff that has never seen a shelf in their life!
No doubt, knowing your supplier is the key to knowing what you are going to be getting in the mix for sure.