Finally! An excuse for making terrible coffee! The coffeemaker is dirty - since soap and water aren't working, the tar I've produced is clearly not my fault. Or not ...

MSNBC claims calcium deposits can be cleaned with vinegar:

Pour 2-3 cups of water and an equal amount of white vinegar into the water chamber

Hit the brew button

Turn the machine off halfway through the cycle and let the solution sit for an hour

Turn it back on and complete the cycle

Run two cycles of plain water through the machine to rinse out any vinegar before using it for your morning coffee.