@Julo - not only does it work, it works so well that I'm still doing it. Had it been something that did not generate at least 5 figures a month for me, I would have stopped a while back.
Read this post in that thread - [link removed because BHW gives me a "spammy conetent"message, they need to fix this]
That may give you some light on how some others are doing.
And @Jeffersontalks is accurate in what he is saying. You don't spam groups but rather offer relevant content that adds value to groups in order to not come across like a spammy salesman in order to generate targeted traffic that converts.
5 figures a month? Without even using an ad or campaign? Now I am really amazed.
I think the only thing that can bring that much profit is very good quality content that can engage people, the problem is how do you get it? I know you said copy/pasted other websites but that will screw your site in terms of SEO plus the copyright issues.