Practically everything about the quality of their work is an externality to a contract cleaner - it doesn't affect them. If the toilet looks mostly clean and they won't get fired for it, that's good enough. If the paper rolls are loaded the wrong way around for the dispenser and they're glued together, that can be a frustration for anyone who uses the bathroom, but not to the cleaner if it won't get them fired. If the floor is vacuumed in all the major traffic areas, but not behind the plants or under the stairs every day, that's good enough. Pretty much everything falls into that category. It is in their best interests to do their job just barely well enough to avoid getting fired. That is the only way their work directly affects them.
Mokalus of Borg
PS - Once you start noticing half-hearted cleaning, you keep seeing it everywhere.
PPS - So, I guess I'm sorry for doing that to you.