What to look for:
AROMAS AND FLAVORS - Free associate as you smell and taste the spirits, and jot down the descriptive words or phrases that come to mind. Make sure the Tequila is clean, that is, lacking such obvious faults as a vinegary quality, mustiness (which may be due to a bad cork), oxidation or a strong suggestion of the barnyard.
TEXTURE AND WEIGHT - Is the Tequila light and crisp? Is it soft and full-bodied? Is it rough or smooth?
TEMPERATURE AND SPICE - Is the Tequila hot and spicy or sweet?
OVERALL BALANCE - Generally speaking, a good mature Tequila should display a harmony of components; no single element should dominate. But perhaps your Tequila is overwhelmed by scents of the oak barrel in which it was aged or is excessively peppery or alcoholic. That's not a good thing, unless you like oak and pepper.
PERSISTENCE ON THE PALATE - If there is a single reliable indicator of Tequila quality, it's the length of the aftertaste, or finish. A Tequila that disappears virtually the moment you spit or swallow it probably lacks concentration or was made from marginal ingredients. An outstanding spirit lingers on your palate for 20 to 30 seconds and sometimes much longer.
Choosing the Proper Glasses
The glass matters a great deal in Tequila tasting, with the size and shape affecting the trajectory and intensity of the aroma. Several years ago, German manufacturer Riedel designed a Tequila glass at the request of Tequila manufacturers.
With their long stem and shape that resembles a sparkling wine glass, they add a note of elegance to any tasting. A transparent Tequila glass will allow testers to identify the purity of the liquid and to evaluate subtle differences in color.