How to easily clean your microwave:
Take a microwave safe bowl and fill it with water. Add a dash of vinegar. Set it in inside and turn the microwave on for 5 minutes. The water will turn to steam and the steam will soften up all the gunk. The vinegar helps to absorb the smells. let the microwave sit for a few more minutes to let the steam penetrate even more if you like.
Be really careful when opening the microwave and taking the bowl out. The water will be extremely hot. Wipe down the walls with a damp cloth and remove the plate from the inside. Rinse it in the sink with hot soapy water. Put the plate back in and voila, a nice squeaky clean microwave ready for the next person to cook something and forget to cover it!