You should describe *in detail* in your contracts and proposals what "maintainance" or "management" means - this will decrease trouble later. Also spell out that you will not be responsible for posting content, but you will provide a WWW interface for them to do the posting. This might decrease some of their "HTML fears." :-)
You should also explain what management does mean, as by now they're probably scratching their heads and saying "Well if he doesn't post content for us then what are wepaying him for?" For example, "I will make sure the site is up and running, handle user comments and complaints regarding the site, and provide troubleshooting services..."
Hope this helps!
Michael
DISCLAIMER: I am not responsible for the results of anything that I have posted in this post. I'm not a lawyer. :-)