Coffee Quality

The quality of the coffee bean is the most important of these factors, if you are going to buy "good" coffee. The very best bean will taste bad if any one of the other listed characteristics are out of place. Not all coffee beans are equal, but the other points listed above will even the field.
A lesser coffee that has been freshly roasted and ground is many times better than coffee that has been roasted and ground then left to get stale - no matter how good it was when it was fresh.

A can of coffee found in the supermarket often contains large amounts of robusta, low quality Arabica beans and past crop (old) beans. To make matters worse, there is no way for the major coffee companies that roast and ship all over the country to get you truly fresh coffee.

Once you have coffee that has been freshly roasted and ground, good water and brewing equipment free of oil residues from the last brew and the quality of the coffee beans makes a huge difference.

How To Tell Coffee Quality
Please note that a coffee can bought in the supermarket often contains a blend of Arabica and robusta beans, while most coffee houses sell only Arabica beans. Arabica beans are normally rich in flavor - while robusta beans have more caffeine, less flavor and are cheaper to make.
There is an exception to every rule, and the exception here is that some very good espresso coffees will have small amounts of the highest quality robusta beans available on the market. This should not, however, be taken as a guarantee that a coffee house will have any better coffee than the diner down the street.

If any of the previously discussed items, such as cleanliness or freshness, are not in order then even the very best coffee can be made to taste bad.
When you buy coffee, whether it be in a coffee house or in a supermarket, you want to get 100% Arabica - except for espresso blends, which may be a combination of both. Whether good quality robusta can improve the flavor of espresso is up for debate.

For absolute freshness when buying in a coffee house, it is better to buy popular blends that move fast - while buying in a supermarket, vacuum packaged containers with an expiration date are your best bet although all canned coffee will be stale to some extent.

Source : articlesbase