What do the "legs" on the inside of a wineglass tell a taster?

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.
Dear Dr. Vinny,
What do the legs on the inside of a Riedel glass tell a taster?
—Ron M., Seymour, Tenn.
Dear Ron,
Not much, I’m afraid. “Legs” are those streaks that trickle down the side of any wineglass after you swirl it (though they might be particularly beautiful in a Riedel glass, they are not exclusive to the brand). The legs are caused by alcohol, so it’s thought that the more legs, the higher the alcohol content of a wine. But most wines are within a few percentage points of one other, and I find that “reading” legs is less useful than reading the actual alcohol percentage on the label.
—Dr. Vinny