Wow, thanks for this thread. I had similar problems to this and kind of figured that it was just a design flaw and I would have to live with it until I could afford a better burner. There was huge amounts of orange in the flame, and lots of soot on my brew kettle, which seemed wrong but i just couldn't seem to adjust anything that helped. Once I opened up the burner though, there was a bunch of metal around the rim of where the air/fuel mix enters the burner. So much, in fact that I hesitated a bit before removing it, almost wondering if it was there intentionally.
Once the extra metal was gone, the difference was unbelievable. I haven't yet done another boil, but based on the apparent improvement in the flame, I think that on top of saving some clean-up, this might just save me a little gas as well.
If you have a burner like this, it is seriously worth your time to pull it apart at least, and have a look. It seems like there is probably a significant quality control problem, but at least it is very easily fixed.