The lesson
Make your deck prove its own claims: footnote every number and print the line that sponsors normally have to go find themselves.
A Pitch Unfairly deck rebuilt from a sponsorship prospectus, with a "Promised / Delivered" toggle. The cover headline carries a footnote marker ("private island¹"), and the slide titled "Who comes, with a footnote on every number." has a "Show every footnote" button. A tier table adds a row, "An audited attendance report", tagged NEW.
A slide on this deck says tiers and prices are the deck's illustration, so don't reuse the sums. Keep the habit of a source line under every figure.