I think having scripted demos that hide error messages is sketchy, if you're representing the demo as "being your product". You're saying "this is my product" a

I think having scripted demos that hide error messages is sketchy, if you're representing the demo as "being your product". You're saying "this is my product" and you're showing something that "isn't your product". Doesn't mean I'm against demos - but normally you can come up with a slice (or two if you're lucky) through it that genuinely works and shows for a representative scenario (and if your arm's twisted you just say that with more money, you can support more scenarios).