I have just enjoyed reading "Evaluating Commercial Counter-Forensic Tools" by Matthew Geiger from Carnegie Mellon University. The paper presents failures in commercially-available applications that offer covering the user's tracks. These applications perform removal of (presumably) all footprints left by browsing and file management activities, and so forth. To make a long story short: seven out of seven such applications failed, to this or that level, in fulfilling their claims. ...
The next thing I was wondering about is how come these products sell so well, given that they do not provide what they state they do, in a way that is sometimes so evident.
I think a partial answer to why these things sell so well might be found in the debate about security as viewed as a market in insufficient information. It has been suggested that security is a market for lemons (one where the customer does not know the good from the bad) but I prefer to refer to security as a market for silver bullets (one where neither the customer nor the supplier know good from bad).
Either way, in such insufficient markets, the way sales arise is often quite counter intiutive. In a draft paper (html and PS), I make the claim that sales in the market for security have nothing to do with security, but are driven by other factors.
So, once we appreciate that disconnect in the market, it's quite easy to prediuct that vapourware sells better than real product, because the real product has higher costs which means less marketing. All other things being equal of course.
Another partial answer is that the bad guys that do need to evade the FBI (and competitors) will know the score. They also know something that shows them
to be generally astute: they generally mistrust privacy-oriented technology as being fraudulent in claims because it can't be easily checked up on. So sales of products will tend to go to people who believe claims - being those who actually have no strong reason to rely on the claims.