Here’s a neat tip - if you ever want to temporarily disable the “personalised” results that Google returns when you are logged in, simply add “&pws=0” to the end of the Google query string / URL. 

For example:

http://www.google.co.uk/search?q=search+marketing

versus:

http://www.google.co.uk/search?q=search+marketing&pws=0

You should see different results – depending on what you have searched for (and clicked on) recently.  Try it yourself and see what differences the Google Personalisation filter is making to your search results – are the personalised results better or worse?