The best defense are the guest reviews coupled with your communication with them prior to booking or shortly thereafter. Still you can have a guest that mis-uses your space and is not respectful of your listing.
I read your reviews which are generally very positive. I suggest you work on your responses. You are posting your response as part of the reviews seen on your listing. Mentioning issues not visible in the guest review is confusing to potential guests so it is best to be gracious and thank the guest. If issues are in the public review, your response should be appreciative of the feedback and indicate if you have taken steps to remedy a problem. Potential guests just want to see if the host is professional and responsive.
I hope you provide an honest review of your last guests as host do depend on reviews. I would imagine you would not want to host them, so a thumbs down review is called for. While the "ick" factor is unpleasant, it doesn't appear that you sustained damages and are planning to make a claim. While Air BNB is guest leaning, if a guest stayed in a place and did not leave because of "unsanitary conditions" a refund is not usually granted.