What is a bad cup of coffee?!

Coffee is a very complex beverage, much like wine. It takes time, tasting and experience to become proficient in identifying it's many flavor notes. Good coffee is not something you're going to find at a grocery store or a Waffle House. You probably still won't find it at Gloria Jean's, Barnie's or Charsucks and it absolutely isn't found at the Golden Arches. Really good coffee, in the U.S. at least, is sadly still mostly an underground sort of thing. You need to seek out a true coffee cafe in your area and start to develop a relationship with the baristas who work there, they'll start you on your journey. These cafes are usually local and are rarely part of a large national chain. Inside you'll usually find 2-3 head semi-automatic espresso machines, locally or in-house roasted coffees hopefully with a roastmaster employee, knowledgable baristas, fair trade organic coffees, and usually a cool vibe. If you tell the barista you're trying to learn the nuaunces of specialty coffees they will probably start you off with a basic espresso shot, straight up. That's the building block so you need to learn what's good from the get go. Anyway that's a start...oh and do read CoffeeGeek. You'll learn more there than you ever wanted to know.

http://www.coffeegeek.com

Coffee that has been boiled (it should never boil, only simmer) is bad, as is coffee that is held in the pot for more than half an hour. More than half an hour in the pot and the coffee should be tossed.
Naturally, if coffee is burned it is trash, and coffee that has been improperly measured so as to be too weak or too strong is less than desirable.
Coffee cooked in a pressure actuated device actually squeezes the essential oils out of the bean without releasing the bitterness, so coffee cooked too long or at too high a temperature will be bitter and unpalatable.
There are a lot of ways to screw up coffee.

Aroma, coloring, strength or depth of flavor. ratio of grind to water, brewing method, and time. Additionally the time that the coffee has sat, and the temperature of the finished coffee will all determine how good it is. Irrespective of sugar/sweetener and milk/cream. If you also know whether the bean is Robusto, or Arabica, and whether the beans have been roasted, frozen, fresh ground, etc will effect the flavor of coffee for real connoisseurs.
On a side note, any coffee that is like the other poster said, ie. over-priced, factory, brew challenged employee made will effect your coffee "experience" as well.

Coffee lover Connoisseur.

Its simply an opinion.
Everyone has one and it doesn't matter if everyone agrees or not.
ITs just coffee.
If your friend wants to act disgusted with your coffee, mildly remind her that SHE's not drinking it.
I put so much flavored creamer in mine that I could be drinking mud with caffeine in it.
There are those coffee snobs around but if they want to spend big bucks on stuff like that and turn up their nose at gas station coffee or cafeteria coffee, let them.

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Enjoy the new phone

Tasteless
Bitter
Stewed
Watery
Boiled out
Weak

Generally all of the above can be applied to every single cup of coffee I have ever had while in the US not one cup would I describe as being a good cup of coffee.

Bad coffee is usually purchased at Starbucks.

Too strong, burnt beans and expensive.


Edit- The absolute best coffee I have tasted was at Cafe Vita, Seattle.

all cofee is bad coffee to me. that cofee might have been good its just her personal opinion. someone probably likes that cofee its just her opinion that its bad cofee.