There have been times when I've seen the tails make a difference, but I'm not totally convinced it's becuase it makes the plug look better to the fish. Scott said it gives the plug better action, and to the human eye, I think it does... look at a danny swimming with that tail wagging off the tail... looks great. On the days that the tails are taking the fish while the plugs without are going unmolested, I attribute it to the presence of small bait. I think and I've seen evidence of this, that the fish are seeing that tail as a small silverside or lance. I have no idea why they would believe that a silver side would be following that close to a larger fish. Which brings you to the question of whether fish really see plugs as fish... or just something that they haven't seen before that might be worth eating???
who knows??