I do not want to scare most people who just LOVE McDonald's burgers. Me included!
But I remember reading in one of my ex-husband's scholar books, that the reason Burger King and Mc Donald's burgers tasted so great, was due to the fact that they put earth worms in the recipe.
Yes, those wiggly little things. The fact of the matter is that the preparation makes them clean for human consumption. As it is, worms are not toxic like most people think. Even though they have a creepy appearance they are edible and nutritious indeed.
Note: I have never eaten a worm in my life, but I have to confess I have eaten Mc Donald's burgers a ton of times.
Since then many people have come forward denying the fact that McDonald's burgers could have any trace of worms in them:
"After a few articles like this appeared, it was simply a matter of time before tales began to spread of McDonalds and other fast-food chains secretly using worms in their burgers. However, worms are in no way cost competitive with other sources of protein such as beef. So there's little reason to fear that fast-food chains will start padding their burgers with worms any time soon."
I must also mention that scientists have sneaked many ingredients, cute and cudley to the foods we eat everyday. Such is the case as the so called "preservatives" and BHT, etc.
In my opinion, if the burgers indeed have worms in them, the ingredients will not mention something like 10% worms, or "contains less than 5 percent earth worms". Scientists have disguised the names of many ingredients from foods for decades to avoid people getting all freaked out about them.
For example, can you guess what alkaloids, glycosides, and diglycerides mean? Perhaps this page will help a bit:
Another question like this can be found here.