Aren't adverts normally tracked (and charged?) by number of impressions and/or click-throughs?
If it was shown on a 404 or parked domain which nobody ever saw, would that not lead to a very low impression or click-through rate?
Assuming the impression/click-through rate was OK, does that not imply that it doesn't really matter what page the ad was shown on?
I suspect I'm missing the point, as the courts have clearly decided there is merit in the case.