MediaBuyerPlanner: Spam messages promoting porn are 280 times as effective in getting recipients to click on them as messages advertising pharmacy drugs, which are the next most effective type of spam, reports The New York Times, citing a report from CipherTrust.

The third most successful variety is spam advertising Rolex watches, 0.0075 percent of which get clicked on. "Successful spam is about impulse purchases," said Francis deSouza, a vice president at Symantec, which makes antivirus software. "Things like home mortgages have a lower success rate than things you'd buy on impulse. Things like Viagra, porn."