I read about the carp secreting the "warning" chemical too. What baffles me is that when they do return and resume feeding they either stay just out of range or, if I can reach them, they swim away from the fly and then start feeding again. Even if I go back a few days later I can't seem to get them to hit. The guy at the fly shop laughed when I told him that I needed to find new fishing spots because the carp seemed to wise up to what I was doing. He said, "Nah, they're stupid. Now, trout are a smart fish." I have to disagree with the first part of that statement!
Let me know how you make out with the woolly bugger. If they won't eat yours they probably won't eat mine either, but we can certainly swap flies and give it a try. It may be an interesting experiment.