One thing to bear in mind is that these contracts start out as rock bottom prices -- otherwise the main contractor wouldn't get them. They are then subcontracted anything up to 5 or 6 times so the man at the sharp end is barely earning minimum wage, and probably considerably less in some cases, so don't be surprised if there's no pride in a job well done because there's absolutely no incentive.
If the customer had any desire to have a proper job done, he/she wouldn't have price as the overriding criterion, but they don't. The requirement is to pay lip service to the need for maintenance, hygiene etc, but not to pay for it.
Like everything else in life, you get what you pay for, or don't, as the case may be.