If you're talking about Tiny Habits, I can vouch for it since I took it end of March this year. Of course my word's not worth much but BJ Fogg does explain about the method on his blog: http://www.foggmethod.com/#large-media and http://www.behaviormodel.org/ so in that sense it isn't like the "fitness/attract opposite sex" programs (scams) you talk about where everything is hidden and shrouded in mystery.

It's all automated via email, so it can be free. It is quite simple and effective but applying the rules in a general sense is something you'll have to master over time.

Also although BJ Fogg has my email address, he's never tried to sell me anything after the program finished, even though I note from his updated site he's got a new certification to be a coach program going on.

Wow it sure does. Only slightly more plausible than "one weird trick".