As with wines, which Armagnac resembles, there is something of an art to judging this fine spirit. But, also like art, there is a range of ability, and there is an element of personal taste. That last should be considered for a moment. Note, that judging brandy isn't entirely a matter of personal taste. There are some guidelines for what qualifies as good or bad, in brandy as there are in art in general.
There is an art to tasting Armagnac, but there are also some easy to learn, objective guidelines. These guidelines help you to consistently rate Armagnacs so you can figure out which ones you prefer as far as aromas, flavors, and structure of the spirit. But there are also the intangibles--how does it make you feel, does it remind you of a treasured Armagnac from long ago, or does the finish warm your cockles?
With some practice, you can extract both the objective characteristics and the subjective qualities from Armagnac. Start with these guidelines.
1. Use clean glassware. I prefer to never let soap touch my tasting glasses. I use very hot water to wash the glasses, and use paper towels or a tight knit cotton cloth to dry them. You can let them air dry if you want, but they will probably spot. As to what kind of glass to taste Armagnac with, I use Riedel O spirit glasses. They are similar to wine glasses but without the stem. They also travel well if you keep the box they come in.
2. Pour some Armagnac into the glass--maybe 2 ounces. Now look at the color. Note what color(s) you see and see if there is any sediment. Note how light passes through the Armagnac--is it transluscent or hazy? Armagnacs are usually some shade of amber--a darker color might indicate longer time sitting on oak.
3. Now smell the spirit. Don't bury your nose in the glass or the alcohol will overwhelm the aromas. Just sniff a few times and write down what you think you smell. Write it down even if it sounds weird. I have written things like "barn yard", "bread pudding", and "brackish". Sometimes on successive sniffs, you may discount what you wrote down and cross it out. Other times, even if you wrote down a rather odd way to describe the aroma, you may confirm what you wrote and keep it. Just don't go into it with any pre-conceived notions.
4.
Now inhale from a few inches away and try to separate the different aromatic hints. Tilt the glass and swirl a little bit to release more. Move your nose closer and take another whiff. Search out those aromas that will only be noticeable from this new distance.
With experience you'll begin to be able to make finer and finer discriminations and to associate them later with flavors. There may be hints of the oak in which the brandy was aged. The longer it was aged, the deeper those aromas are likely to be.
Now taste.
As with any tasting experience, consumption isn't the goal. In fact, if you swallow six different brandies in a short period of time, you're likely to be a little too woozy to judge anything subtle. So, start slow and follow the old rule of sip, swirl and spit.
What that means is simply to take a small amount onto the tongue, then let the liquid travel across it in a little circle. Give the aromas time to spread up the sinuses as the taste hits different taste bud areas. The human tongue is more sensitive to different tastes in different areas.
By the sights you sense through the eyes, the bouquet judged by your nose and the variety of flavors and textures perceived on the tongue a fine brandy reveals itself. Even among those brands that are first rate there are differences. Those, of course, are a matter of personal taste.