While the saying "when in doubt throw it out" is a good one, not all foods with mold have to go. Fruit that has touched other moldy fruit can be washed and eaten, and hard cheese with a bit of mold can be kept after generously slicing the moldy part away.
But if one slice of bread has visible mold chances are the others do too as bread is porous. So lose the loaf. The same goes for moldy sauces and meats. Chances are there is more bacteria below the surface so toss it.
Then there's the question of how long? How long should I keep those leftovers any way? The magic number is three. Eat any leftovers within three days to prevent unnecessary stomach aches.
With over 90 percent of us taking home a doggy bag after dinner, it's important to know how to handle these foods. What most don't know is that food that has been out of the refrigerator for more than two hours should be tossed. The clock starts ticking the moment you are served. So if your dinner experience is a long one or perhaps you catch a movie after, don't bring the food home.
When it comes to the microwave here's what shouldn't go in for nuking: empty yogurt or margarine containers or Styrofoam. All will warp and wither releasing chemical compounds that most likely you don't want mixed in with your food. However, wax paper, cooking bags and paper plates are OK. Glass containers and plastic ware are also generally acceptable, and some are even labeled as such.
Finally, while mom told you it was never a good idea to stand in front of the microwave while it's working, the truth is the microwaves sold in the United States are required to limit radiation levels far below levels that would ever hurt you.