Having been on the receiving end of instruction both at Naples and at three UK schools over the years I'd have no hesitation saying the Naples lot were the happiest and most motivated of any of them. Down the pub the only instructor to complain was the one who'd been furloughed from the airlines post 9/11 and that was born of pure frustration at his career taking a backwards turn. At work he still put his all into it.
The unhappiest instructors I've known in the UK have been the ones doing the least hours not the most.