In this role, they are used to track a companies intellectual property. We did a scan of 51 million web pages recently and found over 15 million Web bugs. On one site alone, we found over 30 Web bugs on a single page. DoubleClick has placed the majority of the Web bugs on the Internet today. There is very little that can be done with current technology.
Web bugs can penetrate most corporate firewalls.
Even if disclosure were to be required in privacy policies, by the time you would open a privacy policy, you would be infected. The only real defense is to have the browser notify you if someone is trying to download Java or to simply turn Java off. This may be impractical for some users. Technology is being released soon that will scan for bugs and block them. However, as with any intrusion detection mechanism, as soon as it is released, someone will probably figure out a way to work around it.