Okay, this one qualifies as a not-so-serious rule. Believe it or not, I learned this from your mama who learned it from her dad and grandpa. Due to her "delicate condition," she is currently on a coffee hiatus. Before I met your mother, I wasn't really a coffee drinker. Though I can't remember when I started, I do know that I dove straight into the deep end and never put anything in my coffee.
Rabbit Trail: In my book, the only drink that deserves extra sugar is good old fashioned sweet tea. It's just in it's own category [e.g. brews from Bojangles, Chick-fil-A, Smithfield's Chicken 'n BBQ, or the quality homemade variety].
So if you're drinking coffee with cream and/or sugar, phase it out. It might take a little while, but once you do, you'll actually be able to taste what your coffee is supposed to taste like.