Well, I made a couple of discoveries in the past couple of days, one good, one bad.
I had a batch of IPA that I'd kegged back on April 2nd. It was my first batch in a few years, so I was far too impatient and rushed things a bit (brewed on March 20th). The Bad
When I first started drinking the beer, I attibuted some of it's faults to it being so 'young' and forgave it and kept drinking. As I continued to drink it, hwoever, it seemed to be getting slightly worse over time - not better.
This past weekend, however, I made a discovery. The ball-lock fitting on the keg I'd been serving from had a very slow leak. Closer inspection revealed a crust of yeasty film around the edges of the fitting, down the side of the keg and even a nasty little puddle of goo right under the keg. After pulling the keg from the fridge, I found more yeast crusties on it. I dumped the keg and cleaned it up.The Good
After dumping and cleaning out the leaky and infected keg (it had clearly been infected - the taste was getting progressively worse and the last glass I had a day or so before discovering this left a faint white ring on the glass), I decided to try tapping off a beer from the other keg, which I had not touched since filling and carbonating it back on April 2nd.
Well, the combination of no infeciton from a leaky connection and allowing it to sit in the keg to condition longer before serving definitely made a difference. Even before I took a sip I could smell a wonderful citrusy, grapefruit-like hop aroma with some subdued caramel malt aromas in the background. The taste was very good and I knew then that this keg was good.
So I unfortunately lost one keg due to infection from a bad fitting, but the silver lining was another keg of the same beer - but MUCH better! Is still has a slight haze, but this now is a beer I enjoy drinking - one I would be proud to serve to my friends.
Of course, I now have a ball-lock fitting to replace - and I'm gonna double-check all the seals on that keg before using it again (and replace any seals that need it).