[Keith White]

Now that a few of us are noticing the number of fish just playing with or nipping the tails of baits (recent stinger successes), does anybody have any views or ideas on exactly what the fish might actually be playing at?

Personally Ben:

I believe tail nipping is more common than we think in saltwater fish. Zander/Walleye are notorious for it. Bass too in certain circumstances.
It's a disabling maneuver. In Zander, It used to be said they will disable or injure a fish meaninglessly ? Now it's found that the Zander return to collect disabled prey at a more opportune time.

Maybe, our tail nippers are doing exactly that. If a bait can't be managed in one move, disable the prey first. Bait falls (explains why OTD is so effective) and also why deadsticked or shaky is an effective presentation.

Just my thoughts but always open to theories because I simply do not have a definitive answer.