I wasn’t specific enough Bullwinkle, apologies I meant “without passengers on board”.
Thanks for clarifying!
Two points:-
Firstly, I don’t believe that type of behaviour is as prevalent as you are suggesting.
Secondly, if the off going crew weren’t in attendance when you arrived at the aircraft, then you are merely making assumptions that they didn’t have a valid reason for leaving the packs running.
It’s very easy to exaggerate the number of occurrences and make assumptions about others behaviour but if you don’t have all the facts, you’re just being as negative as the pilots that you’re targeting.