The only case I know of where they were tested in court was in the UK
and they were ruled invalid, because in the case in question they were
in a shrink-wrapped package and you had to buy it and open it before
you even got to read the terms. The "contract" you accept happens at
the moment of sale and anything that the manufacturer wants to
add later is bogus.
A similar case involved terms for use of a parking lot, but the terms
were written on a ticket you got from a dispenser when you entered the
lot. You didn't know the terms beforehand, ergo they were invalid.
I am not a lawyer (but you knew that).
Anyway whenever there's a "read this verbiage and click 'I accept'"
before you can D/L some warez, I just grep the HTML, find the URL
(there almost always is one rather than some CGI script or whatever)
and go straight to it without reading or accepting a damn thing.
Heck as far as we know the phrase "I swear I didn't eat any bananas
on Tuesday" might be lawyerese for "I hereby donate my eternal soul to
Megacorp Inc, SA, Ltd, GMBH".