Have you ever had a client bastardize the website because they went and deleted or messed with the site
Only once, a long time ago. Clients are aware of what work we will and will not carry out from the proposal and subsequent contract. Any work fixing issues brought up through their changes is subject to an extra hourly charge. If you have a client who does not understand what they can and can't do and what we will and won't do, then they should not be your client - move on.