You always want fresh tasting coffee, so make sure you clean your maker at least once a month (recommended) or if you use it consistently, once a week. While there are many ways to clean your coffee pot, I will stand by the old "waitress" solution as the top way to clean the glass portion. The first issue, if you are going to clean the entire pot, is to make sure that you unplug the unit.
Take a handful (scoopful) of crushed ice or just a few regular sized cubes; add about a quarter of a cup of salt(just enough to cover base of the glass pot and a slice of lemon. Let it stand for a few minutes and then begin to swirl the pot around for a few minutes, getting faster and faster. Dump contents out and rinse, with warm water (if you use hot, you will risk breaking the glass pot). If there still are stains, repeat the process. Let the pot air dry. If you towel dry, expect the fuzzies to show themselves.
In the "good ole days" Grandmother would always smell up the house with one part vinegar to two parts water and cook away! After it runs its course through the coffee maker, you want to make sure you rinse it with warm water and at least twice. I never really cared for this method as it really smells your house up and if you don’t rinse it well, you end up with vinegary tasting coffee.
While the old adage of soap and water cleans everything, it will not enhance your coffee experience. Soap and water in this instance will leave residue and combine with the oils of the coffee and leave you with a nasty taste.
Finally if you are really lazy, there are coffee cleaning solutions on the market in which you can try out on your own. Just make sure you rinse, rinse, rinse!