I have a site dedicated to Marines. The bounce rate used to be at almost 80% meaning they left the site from the landing page. the average visitor only stayed for 30 seconds, so I totally changed the site with a new theme, better navigation and the bounce rate went down to 15% and the average stay was more than 10 minutes. All this according to google analytics. I learned my lesson spend time making sure the site is user friendly, I invested in a premium theme and istalled it and the quality of traffic dramatically increased. All this translated to better click rate with adsense as well so I am about to change all my sites now.