I hate when you're measuring out coffee and halfway through you forget how many tablespoons you've already put in. Kulturamt Neuss spoiled me with prepackaged coffee servings, and now I'm incapable of making coffee the old-fashioned way -- by measuring. You inevitably add more coffee than you need and then it tastes like death, even when you didn't use the pour method!
Along the coffee vein, I hate when I take that first slurp of coffee from near the rim and it dribbles down the side of cup. Extra points if a couple drops hit your clothing.