Adwords provides targetted visitors to your site

If you are an adsense blogger and if you become a member of autosurfing sites, you will be show a site every 10 or 20 seconds automatically. As the sites will be of different subjects, you will not bother to search further any site, unless any material suddenly interests you. Thus your adsense ads are unlikely to be clicked by any viewer of such sites, since they are untargetted visitors. But if you become registered with Adwords program, and place your ads with relevant keywords or your website, you are likely to get only the targeted visitors, though you have to pay for getting those visitors. But the likely rate of clicks received from such visitors could be between 1-5% for adsense ads. If your site also sells affiliate products, then some of the visitors may also purchase the products. In that case you will also earn the commission(which is normally 50-75% of the product price). Thus your profit will be two fold. There is no harm in giving a try for Adwords with a small budget(you have always the option to limit your monthly expenditure to a certain amount of your choice which will always be honoured by Google Adwords). If you get the profits, you can continue further , otherwise you can stop the campaign there itself.