I’ve heard of watering down the gasoline, but this is a new one.
There are two types of coffee that trade. The one you probably trade is the arabica type and it’s probably the same type you drink. These roasts are found at Peet’s and other coffee joints like Star-yucks.
The robusta makes it’s way into instant coffee, canned coffee, and the sludge you drink at a diner for example. IMHO, it doesn’t have much taste.