@HuskyPup. I've noticed that recently, sometimes after i've logged into a Google account, it still gives personalized web results after I've logged out. I'm talking about the pre-G+ personalized web search variety.
To avoid this, you need to add the &pws=0 to your query string to NOT get personalized web results. But even this is becoming difficult with real-time search results. tedster's solution sounds best, avoid it by searching on a completely different browser. Otherwise to be sure you don't have any pws whatsoever, you have to quit the browser to clear the session.