i need your opinion about those sites which force their members to browse many sites to get some points/credits and hence visitors for their own website. I am not sure but i think these are called MLM??. infact just three weeks ago i came across a site trafficswarm.com; i think many people are using this site coz their alexa ranking is around 540; As i think these are also waste of time like auto-surfers.
They are indeed a waste of time. For the most part people are forced to view a site for a certain amount of time (around 15sec normally). The chance of people actually clicking your ads, reading your content or ever returning to your site is very slim. You are much better off using the time, you would spend trying to earn credits, to work on your site and promote it with other relevant sites and improve your content.
It's a waste of time especially if you're using Adsense, None of the surfers are gonna pay any attention to your ads. They just want their free credits.