Once you take in a section 8 tenant you are "stuck" with them for the length of the lease (usually 1 year). If the lease is violated you then have recourse to have the tenant removed. At the end of the lease period you can ask the tenant to move if you are not happy with the program.
I have section 8 tenants in my own rentals. I personally like knowing that I am going to get a rent check every month. The section 8 inspectors come around when there is about 2 months left on the lease and check the property to see if there is any work that needs to be done to continue the lease for another year. They are not only checking on things that the landlord needs to complete, but also things that the tenant needs to take care of. It seems to me that there are more and more people qualifing for the section 8 program.