I used to work at Taco Bell back in the day.  I actually loved working there, even though I spent most of my paycheck on food for me and my friends!

If you're curious what really happens at fast food joints, here you go!  13 fast food facts from a fast food worker.

1) After we cook something, we put it in a holding cabinet and set a timer. When the timer goes off, we're supposed to throw it out. But often, we just reheat the food. So for the freshest meal, come between 11 a.m. and 1 p.m. or between 6 p.m. and 8 p.m. More people are in the restaurant then, so we're cooking and serving new food constantly.
2) That plain chicken breast may have been a healthy choice right out of the package. But sometimes we have to slather it with butter just to make sure it doesn't stick to the grill.
3) Most fast-food joints clean everything, including the grills and drink machine nozzles, with super-concentrated chemicals at the end of the day. If you're one of the first customers in the morning, you may be getting some of that chemical residue on the food or in the drink you order.
4) Those grill marks on your burger? Not real. They were put there by the factory.
5) Most of us will cook something fresh for you if you ask. But if you want to make sure your french fries come right out of the fryer, order them without salt; that forces us to cook you a new batch. Then you can add your own salt.
6) Avoid asking for "extra" of something, like cheese or sauce. As soon as you say "extra," we have to enter it at the register and charge you for it. Instead, just tell us you want us to "put a good amount on there" or "not to be skimpy with it," and we'll load you up.
7) Yes our chili is made from what you think. Meat from old burgers.
8) It makes me laugh when someone comes in and says she's trying to be healthy - and then orders a salad with crispy chicken. At McDonald's, some of those salads have about as many calories as a Big Mac. In fact, a small order of french fries contains four fewer grams of fat than a packet of our ranch dressing.
9) Because we're timed on how fast we get customers through the drive-though...we always prioritize those in line outside over anyone at the front counter.
10) One of my co-workers once got so mad that he spit in someone's food. He was suspended for three days; most of us would never do something like that.
11) Here's a good way to know how clean a fast-food establishment really is: When you get your drink, bend down and look up into the ice chute. If you see mold and other stuff growing in there - which is more common than you might expect - they're not cleaning the machine as often as they're supposed to.
12) Those gorgeous pictures of our food in our advertisements? They're airbrushed and touched up with fiberglass and paint. It probably takes two hours to make that picture; obviously, we're not going to be able to replicate that.
13) Please, please, get off your cell phone. I've had people pull up to the window, pay, and drive away without their food because they're talking on the phone and not paying attention. Then they're mad at me.

Source:  Reader's Digest