I am continually surprised that many people I talk to have little to no understanding of how the Google results page works. If you know that Google’s own proprietary search results are shown on the left hand side of the page and paid search (advertising) is on the right, you are doing well. If you also know that the first three results on the left can be paid results, you are way ahead of the crowd.
I think it can be tough to remember that those first three results on the left can be paid results. They are slightly highlighted and it says “Sponsored Link” to the right of the result, but this almost makes them seem like a special links. I find at times these can be pretty relevant links. If someone has spent enough money to be at the top, they hopefully have spent the additional money it takes to have a good page that the link takes you to. Just have to remember that you are looking at an ad.