Are you defining "clothing snobs" as people who closely examine your garments and determine that they aren't made in Scotland or the right manufacturer and scoff at your attire?
Pretty much...

Here on XMTS I have seen some really splendid jacket conversions and some awkward ones. Likewise I have nodded with approval at some very clever and creative inexpensive formalwear outfits whilst shuddering at others.

Does this make me a "clothing snob"?
Are you the sort of person who says something like "If waiters' jackets passed as formal wear then plenty of people would buy them instead of buying or renting a real tux. Guess what they don't, because they don't look right. Using the excuse that no one else will know is bad form and quite frankly wrong. Certainly there are many people who nothing of clothing who will accept what you wear as the real deal, but plenty others will still see that you are not wearing quality garments." If so, IMO, you're a clothing snob. To the best of my knowledge, I've never read you posting something like that (nor has Matt Newsome or Hamish, AFAIK). A clothing snob cares more about the clothing than the person inside that clothing. I'd like to think that the three of you have more class than that.

Or are these "clothing snobs" the ones who have a well developed fashion sense?
And just what is "a well-developed fashion sense? Fashion is in the eye of the beholder, after all. You or I thinking something looks good doesn't make it the height of fashion. Add to that the fact that what "looks good" today may be panned tomorrow, and I'm hard pressed to decide what a "well-developed sense of fashion" is.