@tangor and @wyweb are correct, in my practice: TCIAR. I give the client plenty of detailed "best practices" warning, with a clear layman-level explanation of what may happen. I repeat the explanation face-to-face and in writing.
That done, if the client insists, then so be it: go with the flow. (It may lead to an occasional dropped client if the client later says in effect, "No, that's not what I meant and you didn't warn me: TWIAW.")