Xyro

They really don't enforce proper food handling guidelines in most junk food joints. It's the top reason besides trying to be somewhat healthy that I avoid them. Employees rarely wash their hands as much as they should, change their gloves, or even adequately cover their hair. Gloves are often wiped on aprons rather than changed--aprons I've also seen taken with them to the toilet or outside for a smoke or garbage haul. Their equipment is used and reused and seldom cleaned or sanitised. Food containers are frequently stored in areas rife with dust (see: human skin) and the kitchens can often be so hot and with such high activity that there are some employees who sweat more than usual, which can also become surprise ingredients in your lunch. 

Burger patties, chicken breasts, nuggets you name it-- they all sit in holding cabinets and time out only to be retimed by an employee who doesn't feel like cooking a new batch. Food which may not have been temped in the first place, let alone with a clean thermometer. Food which is cooked in or on appliances which likely aren't cleaned daily, with their grease traps running over. Food stored in walk-in coolers which haven't been cleaned in 5 years and have mold spots on the ceiling and under the shelving. 

Its just a good idea in general to be in charge of your own food as much as possible. 

@Ohiotaku reminds me of this notorious video.. https://youtu.be/2ao-fSNQaSA (NSFW also language) 

@Wedgy rarely agreed to something that much