When people are buying backlinks to their site, they feel they are doing the right thing. However, that is Black Hat also. Black Hat is not until you are stealing content from other websites.
In the internet marketing world of today, there is no way to play safe without one form of Black Hat or the other. People only call what they do different names in order not to be seen by others as doing Black Hat.
The place of Google even makes the definition of Black Hat SEO more controversial. Should Google dictate what is Black Hat or whitehat SEO? Google tries to dictate the way everyone else should create and optimize websites. To Google, whatever is outside its Webmaster Guidelines is Black Hat. I think that should not be. Google think that whatever they are doing is the correct thing and if you don't follow their rules, your site will be deindexed.
Check yourself very well and you would discover that you might have been doing some things out of the ordinary in order to make your sites rank well in the search engines. Should you not call that Black Hat as well?