The NYC Food Myths thread, particularly Tater's comment about H&H bagels and many of the deli comments, leads me to this: in many cases the "ideal" that some folks are discussing bears only a distant resemblance to the "ideal" that those with deep, long-term familiarity have with that thing.
When the bagel's demise began (early 70s?), my mother used to say that bagels changed because lots of people didn't find the old-time small chewy dense bagels as tempting as the big, fluffy, stuffed bagels you get almost everywhere now. So for a person who never had the old style and might not even like it, how can you suggest an ideal?
I find this true of myself when people oooh and aaah over junk food (see KFC thread a while back). I can't even imagine the ideal because the whole process/experience is anathema to my approach.
Also as a native NYer living upstate, I look at the Tristate postings sometimes with dismay because the standards for, say, a piece of bread or sushi, are vastly different here than NYC, and I feel sometimes that if I post my real opinion about upstate stuff, which is that it usually doesn't meet a very good standard, I'm ruining all the fun. And in a few years, maybe I'll forget what the really good stuff was really like.
That said, I do think it's possible to define some ideals because they taste, smell, and ARE better, great pizza being a good candidate for this.