Spyware companies make a lot of money by delivering ads, but what advertiser would want to be associated with spyware? Gambling and porn sites seem pretty indifferent to how they get their advertising seen, but often you see more reputable companies being advertised via spyware. These companies are usually buffered from the spyware companies by an Internet advertising network, such as DoubleClick, Revenue Science, or 24/7 Real Media. Reputable companies contract with an Internet advertising network to deliver a certain number of ads. In turn, Internet advertising networks buy space on Web sites to get these ads shown to the public. Spyware companies also deal with advertising networks, delivering ads through pop-ups.
So if you want to block spyware, you can go after the ad servers as well as the spyware on your computer. While researching this topic, I found the Network Advertising Initiative (NAI), an organization created by advertising networks to uphold privacy and fair trade practices. The NAI site includes an opt-out page, designed to let you opt out of the cookies generated by advertising networks. I tried it, and it didn't work in Firefox at all. With Internet Explorer, I was able to opt out of cookies by about half of the NAI member networks.
That result was disappointing. Another option is to go nuclear, by blocking ad servers in your hosts file. Every Windows computer has a hosts file, a list of Internet addresses and their associated IP numbers. For a better explanation of the hosts file, read this article. Various Internet users have compiled lists of ad servers. You can add these to your hosts file, telling your computer to look to itself for the IP number instead of looking for it on the Internet. The result is a lot of blocked ads. The problem with this approach is that you will block a lot of Web site banner advertising, cutting the revenue for your favorite sites. There should be a better way to take the money out of spyware. Internet advertising networks should refuse to do business with them, as should any direct advertiser.