A variant of this that has driven me to quit more than one job is having a non-technical manager look at a UI prototype and consider that 90% of the solution. "The UI guys had this page ready two months ago! Why doesn't this work yet?" It's even worse when you present a working prototype. They simply don't understand that the backend functionality is what's doing the bulk of the work, and just because you can see som…
We had a hard and fast rule at my last job. ALL demos were either 100% real, or were mock-ups from Balsamiq. If it looked like someone doodled it on paper we didn’t have to worry it would be taken as working. We came to this rule after far too many incidents where some sort of mock up (Photoshop, HTML, whatever) was shown and taken as done. Then we got the questions (possibly unhappily) about where it was and when it…
As he simply was the marketing/sales guy, in case he found himself cornered he could always pretend that the failure was on the dev/technical side... "see with the support".
He could also successfully sell himself this way: once a billionaire proposed him to be the sales director of some company. He set the meeting at 7AM at the Ritz bar, and got the job (not for long : he had negotiated to keep the perks when leaving anyway).