However, I don't completely agree with the parts I've bolded in:
Imagine that Bob claims to have discovered the great long-lost youth rejuvenation potion of the Mayan civilization. Bob tells you that 100% of all people that have tried the potion say that it works! Tom and Jane have tried it, and they say it works too! Bob isn't going to tell you what the ingredients are because it's an ancient secret. Everyone who's tried it will attest to you that its real, but we obviously can't prove it to you over the internet. If you want to know more, you can come and pay X amount of dollars to see what the big deal is...
Sounds dodgy? Yup, you bet it does. This is where the skeptics gets stuck. They don't believe it, but the only to prove it wrong is to invest the time and money to test it
IMO, the minimum threshold of credibility can be surpassed via information provided at distance
The problem lies in if the kind of proof skeptics (like myself) could ask for is going to be provided by the Mayan rejuvenation potion proponents or if they are not going to move from the IHTBF position.