This article at News.com, by Will Sturgeon is a brief synopsis on research done by academics into thee subject. I found it very informative and hope you will, as well. It won't take you long to digest the information.
I've pretty much quit making judgements about the security of a site. I just make sure I've typed in the url myself, or taken it from a list I've built and maintain control of, then cross my fingers and pray a lot. That I do so little business online is a reflection in part of my distrust, though I also try to buy locally as much as possible, to preserve resources (shops) near enough to me that I can access them quickly if needed.