This isn't really a stupid client so much as a stupid supervisor, but it's worth telling anyway.
I was working a while back with a staffing company which used an MS Access database to keep track of its employees. We'll call this program EmpTrack that was stored on the company server - along with the email, etc. Each of the office desktops had Access links to the database, and everyone who had access to the desktops had access to the data.
Because of this, as you are probably already thinking, data integrity was an issue. The only column on the main employee table that was required was "Social Security Number," which we used to look people up in the system if we needed their address, phone number, name, or other information. However, some Social Security Numbers didn't have other information attached. People wouldn't have first names, they would have the wrong names, or they would have no phone number, no job or company history, etc.
My supervisor opened EmpTrack once on my desktop, and lo and behold, the entry it happened to be looking at before she opened it had, for a first name, the letter "E," no last name or phone number, and for an address, the number "4" followed by a semicolon.
My mind immediately thought, "This is an incomplete entry."
She - my supervisor - immediately said, "Your copy of EmpTrack is broken. Call IT support to get it fixed."
I sat in shock for a moment, and then tried to tell her that I didn't have a "copy" of EmpTrack - that if she were to look up that same Social Security Number on her computer, she would find the same lack of data. She was, however, adamant that I didn't know what I was talking about and that I needed to call IT support to have my "copy" of EmpTrack "fixed."
I put it off for three days, knowing I was going to sound like a moron on the phone with IT support, but finally, she caught me not having done it and forced me to dial within line of sight. After the IT guy picked up, she left, and I, cringing a little, told him that my "copy" of EmpTrack was "broken."
He proceeded to take control of my desktop remotely, open the table view, and then explain to me as though I were a child exactly what I had told my supervisor - that it wasn't my "copy" of EmpTrack that was awry, but instead it was a faulty entry. He offered to delete the entry for me, but I declined, instead asking that he would let me transfer him to my supervisor because she wasn't going to believe me when I told her what it was. He obliged.
The supervisor was eventually promoted, so I didn't have to deal with her after that.
Although it does scare me that she was promoted away from me as opposed to fired.