Contrary to popular perception, at least here in the U.S., connoisseurs eschew the use of balloon snifters. The reason is that balloons allow the aroma to escape too quickly,
…negating a fine cognac's bouquet. Experts prefer to use either a regular wine glass or a tulip-shaped glass, one that curves slightly in below the lip before fanning out again. It is important that the glass be of fairly high quality as the thinner the glass, the more heat the cognac will draw from your hand. Professional tasters frequently use blue-colored glasses so that they are not influenced by the color or haze of the cognac. It is usually served without ice. For a good cognac a cognac glass is essential. It is well-known that Cognac should be enjoyed in the right glass. That is of course, if we're talking of drinking it straight, not as a cocktail or a long-drink. If this is what you're after, any glass will do, but if you want to allow your VSOP, XO or older cognac properly, you will need to give the spirit some space to breathe and unfold all its aromas. A popular glass is the Normann Copenhagen Cognac glass, but there is also the classic brandy snifter. ( Full Answer )