This article is from the Advertising on Usenet FAQ, by Joel K. Furr email@example.com.
Some advertisers noticed that it was only *identical* postings that were
getting cancelled by the spam cancellers, and cleverly came up with a way
to post their ad to dozens of newsgroups while varying a line or two to
make it look sufficiently different to avoid being cancelled.
For example, one book editor posted ads to dozens of newsgroups about his
book, essentially giving a sales pitch for said book, while adding a
paragraph to each article that purported to contain the text that had been
printed about each newsgroup in said book.
It was rather obvious that the editor wasn't interested in getting
feedback on the text since the book had already been published; eventually
an employee at the company admitted that the technique had been used to
try to avoid triggering the spam cancellers -- and that the point had
indeed been to broadcast the ad widely without getting cancelled.
Don't do postings that say things like "Congratulations,
REC.FOOD.DRINK.BEER reader, you are among the lucky few to be included in
this amazing offer." Spam that makes a token effort to relate to each
newsgroup it's posted to is still spam, and will still be erased on sight.