"Show me the incentive and I'll show you the outcome." This popular quote by Charlie Munger demonstrates the importance of incentives.
Using small rewards, in addition to their normal pay, encourages team members to go the extra mile. It can also create healthy competition between your cleaners. A quality bonus for 0 complaints within a certain time frame or a punctual bonus for arriving to all cleanings on time is great incentive examples that will improve your team's performance.