Beck Beer is Cloudy -- Gone Bad?

Some weeks ago, I purchased a six-pack of Beck's Premium beer, in bottles. Green bottles with silver labels.

When I got it back to the apartment, I noticed the beer was a little bit cloudy. Now wait a minute, I don't remember it being cloudy before? I was afraid to drink it. (In fact, I still have it.)

So just a couple days ago, I bought another six-pack from a different location. A location that is, shall we say, a bit more "up scale" than the other place.

Now this Beck's beer is as clear as spring water, the way I remember it!

I know some kinds of beer are in fact supposed to be cloudy, which is fine. But if it's supposed to be clear, then it's supposed to be clear! At least it's supposed to be consistent.

So the question is -- should I pour the cloudy Beck's down the drain? Or risk drinking it?

What kinds of ways can bottled beer go bad? And how can you tell, other than tasting it? (Get somebody else to taste it!)