Owning Bitcoins doesn't make you more trustworthy. Allowing someone trusted to review what you sell, does. And no one has reviewed yet.
Agreed, a signed address with bitcoins doesn't prove my method. That's the reason why I'm accepting escrow, but there's no need to hand out the guide to a trusted member for free if we are using this way:
Buyer will send bitcoins to escrow, I'll pm the buyer the walkthrough, buyer will release the bitcoins. If you think the provided method will not work you're free to claim a dispute and the escrow will decide.
With this scheme there's literally no chance to scam anyone.