How often do you actually analyse what makes you click on ad?
Looking at the good old travel sector for example, if you did a test search, which ad/ads would you click on? Would it be the top ones? Why would you chose them? Just because they are at the top?
What jumps straight away in your eye? Do you just look at the titles and ignore the rest? Do you concentrate on the display URL? The first word/words of the description line? It would be interesting to discuss a few "test results", maybe we will get some new ideas we can feed into our campaigns.