I reckon Estey has summed it up. I'm guessing a place like Booroomba might have very few three star climbs but stacks of two star and one star routes. You generally cop the most criticism when you award three stars to routes, because expectations are so high. For example that multipitch combo (I can't remember the name) that you and Gareth and I climbed (as a potential candidate for Classic Climbs of Australia) would be better off getting two stars in my opinion (a must-do for Booroomba at the grade but might not classify as such a great route elsewhere).
With regard the cobweb symbol, maybe you should use it in the same way that Rob applied the hand (warning) symbol in the Point Perp guide. He always had comments after the hand symbol to explain the warning in more detail. Comments after the cobwebs symbol could be along the lines of 'A two-star route if clean. An awesome test-piece if you are prepared to do some brushing beforehand'.