[aussiblue]

Of course the reality may be that:

a) most modern cars have good corrosion protection;
b) the peddlers of electronic rust protection devices know this;
c) because of a) the risk of significant corrosion on a new car fitted with such a devices is minimal;
d) because of a) many who fit these devices will think they work and give the product a good review; and
e) because of a) and b) the peddlers of devices can take insurance at relatively low cost to settle any claims if any corrosion occurs.

But I'm a cynic as well as a skeptic.