I don't believe much those sellers that claiming the methods as their own but the truth is not, I think they have just got it from the internet shared by generous geek guys maybe on other forums and blogs. There are really lots of them so always make a background research, we can learn by self study.
Mistakes happe with everyone. It's our responsibility to learn from the mistakes rather than just spending to get the teaching of someone else. Learning from the life reality and experience will never be got through any of the books or blogs. Make yourself prepared and move in which you're passionate about.