AAFCO = Association of American Feed Control Officials 

AAFCO feeding trials consist of at least eight dogs being fed the same diet for 26 weeks. During this time, 25% of the dogs (so, two animals) can be removed from the test and the dogs eating the food can lose up to 15% of their weight and condition; the food will still pass the test and be labelled "complete and balanced."

The AAFCO protocols were NOT designed to "examine nutritional relationships to long-term health or disease prevention"  If a dog lives for six months with no noticeable ill effects on a kibble, then the food is considered 100% complete and balanced nutrition, even though long-term nutritional deficiencies may occur several years down the road.

AAFCO  add a little further insight into pet-food manufacture in the following document:

http://www.aafco.org/Portals/0/Public/Q-AND-A-REGARDING-PETFOODREGS.PDF

I particularly like the paragraph 4:

"4. Am I correct that parts from sick, dying, or dead animals are allowed? Doesn't this pose a health risk to pets?

Animal by-products which may include materials from animals which died by means other than slaughter are explicitly defined as adulterated unless the materials are rendered in compliance with animal health and protein product regulations to destroy any potential microorganisms which may be in the products. The processes used are deemed to be adequate to control risk of disease."

This should reassure you knowing that when foods are made using animals that died from disease, the bits are cooked at high temperature to kill off all the bugs!

Is this actually dangerous to your pet? I guess the answer is "who knows" - if you don't know what is in the product, you really cannot say it is free of risks - nor can you say that there is a risk!