Internet is wide an if you are not prudent you can get scammed everydays. Here are a few tips you should keep in mind while browsing the internet :
Those products are often promoted on websites like squidoo or hubpages and sold through Clickbank.com.
2) Avoid Acai Berry free trial offers. You will often have problems cancelling the trial ( http://www.complaintsboard.com/complaints/can039t-cancel-free-trial-c172308.html or http://acaiberrysite.com/beware-of-free-trial-offers-for-acai/ )
3) Avoid answering to unknown people Sending you messages through Myspace or any other social network. They are just doing e-whoring ( Chatting with people in order to earn money by making them signup to cam or dating websites ). This simple google search : http://www.google.com/search?rlz=1C1GGLS_enFR321FR321&sourceid=chrome&ie=UTF-8&q=e-whoring will make you understand what e-whoring is
4) Check what you download. Companies are paying people to install spyware on your computer. Theres even a forum dedicated to this : http://www.pay-per-install.org/.
5) Avoid ptc companies (such as bux.to), 99% of them are scams and will never pay.
These tips are simple to follow and should prevent you from falling into internet scams. As an additional advice you should always search for an company reputation on google before buying a product from it.