Let's be realistic about this - all hosts should be responsible for the condition of their listed property - not a cleaner. Either check the place yourself, or employ a site manager or someone with the ability to overview the property to ensure high standards are being met.
Most guests do not book a property just to try to get a refund later by 'pretending' there is a cleaning issue, so I would have to say that the number of guests complaining should tell you (and Airbnb) something. Harsh - but the same applies to all of us hosts.
Perhaps another booking site would be more tolerant.