I was on this flight before and it wasn't as bad as you thought. Since I board the flight from JFK. During the stop at YVR, we are requested to stay in our seat while the aircraft was being refueled and replenish food and drinks, as well as cleaning up aircraft during a short period of time.
When the flight was about to board passengers from YVR. The cabin is clean and ready as it was when I board in JFK. So do not worry about no one is cleaning up the cabin. The process might be a bit hetic and rush, but the cleaning crew will do their job well.
And I had a great sleep before I arrive in HKG the next morning.
=)