What is the best way to clean red wines stains from a wide-base decanter?

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:
Can you please tell me the best way to clean red wines stains from the wide-base decanters? Regular cleaners and soap leave an odor. I've heard all kinds of solutions, such as potatoes, rock salt and soda.
—Michael Graham, Vancouver
Dear Michael,
I'd love to see you clean a decanter with a potato. Heck, I'd pay money to see that. I like to use hot water, baking soda, and one of those stemware washing brushes that are made out of soft foam and squeak when you use them.
—Dr. Vinny
Dear Dr. Vinny:
I've been a waiter for several years and have always been told that the deep indention (punt) on bottom of the bottle was a serving aid. But my girlfriend attended a wine tour in California and claims that the deeper the punt, the finer the wine, because it has something to do with pressure. Please help us!
—Mikel Steen & Tammy Lea Bickel, Ft. Worth, Texas
Dear Mikel,
You can tell your girlfriend that size (of a punt, that is) does not matter.
Punts are a leftover feature from days of yore, when glass was weaker and bottles were made individually by glass blowers, who added the punt to strengthen the bottle (this was especially useful with Champagne bottles, in which there is constant internal pressure). Modern glass is much stronger and bottles are machine-produced, so there is no need to keep punts around, except for tradition. Some suggest that punts help collect sediment or make it easier to pour the wine if you have super strong thumbs. The truth is, it's just an aesthetic tradition. Moreover, big punts can make a bottle look like it's on steroids. Hello, marketing.
—Dr. Vinny
Dear Dr. Vinny:
I have a magnum of Ponsot Clos de la Roche 1978 that I have up for sale. However, the label on the neck with the vintage has fallen off. If I remove the capsule am I likely to find the vintage on the cork, and if so how will this alter the price? Or should I just invite a bunch of friends over for dinner and enjoy the wine ourselves?
—Jason Uller, Los Angeles
Dear Jason,
I have a Picasso that Jackson Pollack dribbled paint on, and when I tried to scrape it off it started to look like a Rothko. If you have a single bottle of a wine whose label is not in very good condition, your chances of selling it for a bundle on the auction market isn't very good. Most collectors like to buy wines in quantities that were stored in well-documented conditions. I'm not questioning the validity of your bottle, but then again I'm not an auction house who would risk angering a patron if I sold your bottle. Find an occasion, invite some friends over and pop the cork. That's my answer to many of life's persistent questions.
—Dr. Vinny