I have been running some test on Google personalized search, although the all results aren’t in yet, there does seem to be some loopholes 
With Google Personalized Search ON: ( I added the yellow box)
We are working on %’s at the moment, what will trigger a result and what won’t… I triggered the webmasterworld result Via spam for my Google Personalized Search … But it would be easy to spam for any site .. in fact Google Personalized Search opens an new set of spam doors
Google Personalized Search OFF
