I read labels religiously. Not so much to find American made 'stuff' (although if that's the better product - or a horse a piece - I'll certainly choose US). When it comes to food though, I'll always buy local if possible. Organic is preferable (and I avoid corn syrup like the plague).
Like Dejibo, I try to find the best pet food I can and that's no easy thing becuase most of what's on the shelf is crap. (I'll buy Wellness, Pet Guard or Paul Newman's).