I'll agree that the worst is the empty one, but the next worst thing is the paltry dishwater-weak tea-like stuff some people make. Worst coffe I had was in Indiana. It seemed like the closer one gets to the middle of the US, the weaker the coffee is.

I worked in a clinic, and one doctor and I tried to sneak in there and make the coffee with some actual coffee in it before others did it. People complained it was too strong, but you can dilute coffee that's too strong. If it's too weak, you can't do much... unless you steal a filter, stick some coffee in it and dip it in your cup like a tea bag. Done that. It's tricky not to scald one's fingers.