I became really good friends with the owner and since I was working freelance from home I would often go down in the afternoon and get a glass of wine.
I learned a lot about wine, but the most important things were the following.
Wine experts don't judge the quality of the wine but the quality of what the wine is supposed to taste like based on it's appellation controléé http://en.wikipedia.org/wiki/Appellation_d%E2%80%99Origine_C...
Those criterias are the "objective" criteria and those are the ones uses to judge a wine by. The particular taste of the wine is less interesting (i.e. the experience that normal people would have of the wine)
Being a wine expert does not mean that you know good from bad wine but that you know what any given wine 1) smelled like (cherry, toast bread with butter, apple etc). The owner had a set of 100 little bottles each with it's own smell.
You would be surprised how hard it it to pin point the correct word of the smell of one of those bottles, even if you recognize the taste.
Once in a while I would be involved in some of the wine tastings and see him and his friends guess if not the exact wine then the actual zip code.
One of the most important things he taught me was to find the balance of your food and your wine.
It's one of the things I have found most enriching of my culinary life. That and the ability to smell (not taste) whether a wine have cork (impresses the girls and gives you an advantage in any business dinner)