This may sound like a silly question but what is a professional SEO?? Before anyone answers think about it. Would the answer be results driven in a given window of time? Would it be performance driven? How can there be professional SEO's when this is not something you can go to university for..."Hi I am a professional SEO graduating from Ryerson" Algo's and rules change so fast I can't see, honestly, anyone claiming this. And further promising results for money spent.
Since Google's latest algo RIP SEO. Link mongering is where it is at.
So son what would you like to be when you grow up?... a doctor, a lawyer perhaps a dentist no, no...how bout a link monger?