Last Saterday, Jan 24, we had another wine class at the Porter House Brew Shop. It was a good class and I am happy to be back teaching after the holidays. The number one thing I try to pass on to my students is to keep EVERYTHING that touches the wine sanitized. Bacteria and wild yeast are everywhere and they can spoil your wine if you are not careful. Some people think that the alcohol in the wine is enough to keep everything clean. That isn’t the case prior to fermentation. So make sure everything is sanitized from the time you start until the wine is in bottles.
If you think the alcohole in wine is enough to keep it from spoiling, leave a glass of wine on your counter for a couple of weeks. I seriously doubt you would want to drink it after that long. 
Enjoy your wine.