There are a lot of poor excuses for coffee out there. I'm not a coffee snob, but what you get from Dunkin Donuts, McDonalds, gas stations and convenience stores are a bad way to judge coffee as a whole. Usually they're bitter, burnt-tasting, or so sugared-up that it masks the coffee flavor entirely.
I'm not a huge fan of Starbucks, but I got a 2oz espresso from them while I was up in VT on vacation, and it was pretty decent. It's strong (of course), but surprisingly not as horribly bitter as their regular brew.
Oddly enough, in college, one of the cafeterias had a Maxwell House coffee machine that made cappuccinos. They always came out amazing, except for the time it tried to give me a large when I selected medium, and pissed coffee all over the place...