On August 08-13th I bought backlinks on 6 strong sites (with traffic) homepage sidebars for 2 of my similar sites. The sites are couple of years old, having similar backlink profiles before - WEB2.0s, profiles, forum posts, etc.
The result:
On the same date range I also bought links in the content on very strong sites homepages with huge amounts of traffic for my 3rd site:
There is big drop few months later after these backlinks - I redirected this non-performing domain to a new one (fresh).
The result:
I trying to do good on-page SEO, fast sites.
Maybe this is too much? My sites has headings and 1k words of text, while competitors does not have any text at all and slow websites, and ranking good.