was part of a company that was putting out mass market tv/radio ads. i was in a group that got some previews and we were asked for feedback. "Save up to 30%" and "save up to 40%" were phrases thrown around. I mentioned that our average customer was actually saving closer to 50% (often more), and asked why we didn't just say that. Head of marketing guy said those numbers were generally not believed by most viewers. I was only there a few months at that time - they'd been running variations for years, and had some numbers to back that up (website clicks, call volume, etc). We could have said "up to 45% or more!" which... is technically 'true', but confusing and awkward to anyone who parses the whole thing. And "save up to 53%!" just didn't come across as believable, even when we had the data to show it.