AAVA's
If I was offered an AAVA tomorrow, I'd do it, no questions - I'm that strapped for cash at the moment.
If the Union decided to use AAVA's as an official bargaining tool, I would not do them, despite being strapped for cash.
As PPRuNe Radar states, it has to be official to be legal. Now we all know that we cannot be forced to do AAVA's, but until it's an official tactic from the TU, then the majority of people will do the odd one or two