First, a definition. Narrative Control: Making positive something that is or will be perceived as negative.
If you have an unexpectedly good offer (for example, your product does something most products can’t, or you’re giving a discount that’s way better than most) then you need Narrative Control.
To illustrate I’ll show an example where Narrative Control isn’t used.
On CNN.com I saw this giant top of homepage banner (translation: it’s super expensive):
On click I was taken to this landing page:
77% off is an incredible deal (see headline). 30% of the people on this page will see this ad and say:
“Hey, that’s amazing. I’m so happy I clicked the ad”.
70% would say:
“I don’t buy it”
If the page also included a message to explain a little about how they achieve this 77% saving it would have an incredible impact on the skeptical shoppers: