Yeah although ad buyers of any sophistication knew going in that a lot of certain newspapers were hotel copies (though arguably a lot of people read those), trade rags vs. consumer subscriptions, general vs. niche, etc. and took that into account.

They still didn't have a great idea of how effective they were a lot of the time of course.

Printing a newspaper at least costs a bit more money and there's a decent chance someone will read the copy of the paper in their hotel room. Fake Web traffic could easily dwarf real traffic.