How do they stay out of jail? There are laws against fraud, right?
A couple of points. First of all, you can break laws all day long, and as long as no one bothers to prosecute you, you can continue as long as you want. It takes money to prosecute people, and prosecutors have limited budgets. Also, a prosecutor has to be both interested in prosecuting, and have jurisdiction for the relevant area. If the fraud is taking place in one state, and a prosecutor in another state is interested in prosecuting, nothing will happen unless they can convince the authorities in the relevant jurisdiction to take action.
Second, in these kinds of cases, the claims are typically sufficiently vague that they may be difficult to prosecute (please note, however, that I am not a lawyer, and, even if I were, laws vary from place to place, so you should not regard anything I say as legal advice). And in the case of:
http://cls.audiogon.com/cgi-bin/cls.pl?accsrack&1207742831
I could be mistaken, but I don't see any claim for improvement at all! If they do not claim anything, then how can there be a case of fraud at all?
And at:
http://www.machinadynamica.com/machina31.htm
Again, what claim is made for actual performance? If no claim is made, then how can it be fraud?
Besides, there are plenty of phony psychics around, and plenty of phony faith healers, some demonstrated to be frauds (like Peter Popoff, who was exposed on national television in the 1980's, but was never prosecuted for fraud, and can currently be seen on TV doing the same kinds of things as he did before), but they are not usually prosecuted either. See:
http://en.wikipedia.org/wiki/Peter_Popoff
If you want the government to protect you from all of those things, you should vote for BIG government. VERY BIG government, as it would take an army of lawyers to prosecute all such people.