I find them inconsistant Tom. I hear some guys swear by Code Blue and James Valley but I've never found these two to work. Mostly I've used them on drags. Two things I haven't tried yet is using them over a mock scrape and the Buck Bomb. The most consistant attractant I've used is the rattle bag.
I've tried them close to bait near a well used trail. If anyone has a method that is consistant I am listening.