Put something in the contract where if they need you to handle vomit, spills, toiletries, etc a fee will be charged. This way you do not feel like crap every time you go out there to please them. Also, it will limit the times they ask you to do so. This is the rough side of Janitorial work, most are never satisfied and no one wants to pay. I offer higher end pricing because I know that some people are a pain to deal with and as business owners we just want to please them.