The floppy fish CAN be caused by over use of the rudder as much as stirring the stick, and is the same thing.
And no it is NOT a legitamate tactic. It is quite simply a situation of taking advantage of the nature of lag/the internet, and the smoothing code in the game. Not to mention the near instantaneous control reversals that are possible with no stick forces and digital joysticks. In real life this was simply not possible.
Todd, your counter is only good if your in a turnfighter with a nice low speed stall. If your flying a BnZ plane the floppy fish is a very viable defense against you, as it will cause the attacker to repeatedly miss. And quite often even give the defender a chance at a reversal if the attacker gets impatient and overshoots at a slow speed.
If a person uses that kind of manuever, and gets called a "dweeb".... they shouldn't be upset, because thats what they are !