I saw this on an otherwise respectable website.
Maybe I’m too modest in my approach to communication, but I would never say something like that about a service or idea I offered. For one thing, it is simplistic. For another, it is not modest in any way — the claim is that the person who clicks there will get guaranteed results. If the vendor actually did guarantee the results, that claim might be believable.
We are all too smart today to believe claims like that. When such claims are made, most intended clients will shut down the message and not go any further.
Takeaway: Promise what you can truly deliver. Otherwise, give a visible footnote or two explaining that most people find your claim to be true.