I am not sure if this is trueor not.
I heard that some burger kind staff spit and put even worse things in the fast food.
There was a claim on the news that some guy opened up his cheer burger to finbd flem in it.
I also saw a under cover type of documentry on tv about burgerking and the staff spat in the burgers and they caught it on camera and also some of the staff adminted to putting other body fluids in the burgers.
The people who where caught on film where fired so it said on the documentry.
There was also this lady who worked for burger king who had the flu licked certain food and gave it to the customers so that they would catch the flu.
I believe that this could go on and i do admit i check my burgers when i eat out just to be on the safe side.