I don't really like talking about beer with people because most people haven't a clue about the subject. I know. That sounds a bit elitist. Lots of people drink beer and lots of people know what tastes they like. But there's just so much crappy knowledge about beer out there. It's difficult to understand what goes into beer when everything related to selling beer is based on some ridiculous image concocted by a bunch of sales goons. So myths develop and people stick by them. However, I found this website and the guy talks about some of the most common defects and tastes in beer, where they come from and how to spot them. A good read for anybody interested in beer at all.
Please note his line in oxidation where he says "you are safest getting beers from large breweries because they almost always have the best quality control." He's speaking specifically about samples for taste testing controls, but still, it's a good point to make. Just because you don't like the taste doesn't mean it's low quality.