The Internet has created vast opportunities to interact with strangers. The interactions can be fun, informative, and even profitable [1]. However, there is also risk involved. Will an eBay seller ship the product in time? Is the advice from a self-proclaimed expert on Epinion.com trustworthy? Does a product from Amazon.com have high quality as described?

The full version of the paper is available at http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6153140&tag=1