It should be "active" in your mouth, a bit peppery, and the taste should linger for a minute or more; it should taste like it's alive. It should be just slightl

It should be "active" in your mouth, a bit peppery, and the taste should linger for a minute or more; it should taste like it's alive. It should be just slightly bitter and you should note a grassy flavor/aroma, like good Japanese green tea, as well as a distinct olive smell. It should be only barely acidic, as inferior oils have more acid. If you're buying in a supermarket, you are almost always buying oil blends from multiple countries. Read the back of the label where a guide tells you where the oil came from; if you're lucky you can find one bottle that only came from one country. If at all possible, check the websites of the different options and see what production methods they use. Go with either first cold pressed (no added heat, pressed with mats to extract oil) or 2-centrifuge process. If you're buying in an oil and vinegar tasting room, sample everything and go with what tastes best to you, because that's mostly the purpose of buying EVOO (in addition to the nutritional benefits of well produced EVOO). Ask the seller more questions and you will probably find that almost all the oils there are centrifuge-made, and they'll have maybe one bottle of mat-pressed oil in the back that's more expensive, and probably tastes drastically different than the rest. You basically want to buy an expensive EVOO, and a cheap olive oil; the difference being that you would use regular olive oil for cooking, and EVOO for flavoring.