The answers to your questions are no and yes:No, in that you cannot be required to "work off the clock"--if you are an hourly employee, you have to be paid for all hours worked, including time spent redoing work which had not been done in a satisfactory manner.Yes, in that unless you have an employment contract--and the vast majority of people do not--you may be fired at any time, for any reason that is not illegal discrimination (that is, as long as you're not being fired due to your race, sex, religion, age over 40, disability, etc. it is legal). That includes being fired for doing a bad job cleaning. So your boss cannot make you clean for free; but she could fire you for not cleaning well in the first place.