Sure there are "yuppie snobs" in fly fishing. Just like there are "redneck jerks" in bass spinner and baitcast fishing. That does not mean all bass fishermen are redneck jerks any more than it means all fly fishermen are "yuppie snobs".
There are sterotypes for nearly all aspects of the sport with people who use worms and minnows being somewhere toward the bottom in the respect hierarchy. It does not mean that all or even a significant number of peopple fit that description, but some do and they stand out and therefore become what others tend to see and key in on.
With that off of my chest, I better finish my double mocha latte before I get in my 5 series and drive off. I wouldn't want to spill any on the seats or stain my khakis.