The problem with AZ is the overwhelming sense that the whole thing is held together with bubble gum and string. The planes are really dingy - among the worst of any major airline. The staff doesn't exactly give off a helpful (or even competent vibe). And having to take a bus to and from every flight at MXP only contributes to the impression that this is not a top-tier airline. What happens, then, is that every bad impression is magnified, and every good experience is (perhaps rightly) tossed up to luck, rather than AZ getting it right.