"but it's a grey area if they've done cock all all day except run up a hotel bill! "
You seem to be saying two things. First that the crew were evading work/duty and second that this is a representative attitude companies must guard against.
In twenty years, not once can I recall meeting a crew member who wanted to do "cock all all day except run up a hotel bill", though I`ve met plenty who were keen to save their expenses and many more who were desperate to get home.
More commonly I`ve experienced crews who want to rest before or after a flight or finish their rotation asap, but hang out in a hotel? Not so much. Also, once in the hotel, I`m not sure how you "run up a hotel bill". Any flying I`ve done or organised has involved the crew covering their own expenses. However, our experiences are our own.
In all cases corporate crews are paid for their time, not flight hours. It makes no odds to me whether they`re sitting on the ground for a month or flying 80 hours, I am paying them for their availability. That`s crystal clear, but even in private ops, fair practice suggests I should identify to the crew when they are on standby and when they`re finished. "Bloggs you`re on at 0600 and off 2000". I`m not defending excessive drinking before a flight, but after a period of standby it`s perfectly reasonable that crews should be free to ....insert leisure activity- go swimming, watch a movie or have a meal and a glass of wine. I would appreciate it if they answered the phone at least if I had need to contact them during their off time, but otherwise, their only obligation to me AFAIC is to present themselves fully ready at the next standby or duty period.
If a company refuses to acknowledge the basic human need for rest and some measure of relaxation and then finds them embarressed because it assigned a flight to an aircraft with no crew, then they only have themselves to blame. Forgive me, but I don`t have much sympathy for a business model that relies on rolling standby and I certainly don`t have any sympathy when they suffer the embarrasment of having a flight compromised because of their policy.
IMHO, if a company can`t operate according to the regulations or fair practice it should leave and allow better operators to succeed.