Dear Heloise: My coffee comes out terrible. I’ve changed coffee brands, used cold tap water and distilled water, and measured my coffee grounds carefully, yet I always get such a nasty bitter taste to my coffee. What am I doing wrong? — C.N., in Texas C.N., are you cleaning your coffee pot carefully and using the right grind for your coffee pot? I’ve found that when coffee starts to taste a little “off,” it’s usually due to a buildup of coffee oils.