While this may be a great concept, the downside is that the advertising companies also install additional tracking software on your system, which is continuously "calling home", using your Internet connection and reports statistical data to the "mothership". While according to the privacy policies of the companies, there will be no sensitive or identifying data collected from your system and you shall remain anonymous, it still remains the fact, that you have a "live" server sitting on your PC that is sending information about you and your surfing habits to a remote location.....
No, but the majority are. There are also products that do display advertising but do not install any tracking mechanism on your system. These products are not indexed in our database.
Even though the name may indicate so, Spyware is not an illegal type of software in any way. However there are certain issues that a privacy oriented user may object to and therefore prefer not to use the product. This usually involves the tracking and sending of data and statistics via a server installed on the user's PC and the use of your Internet connection in the background.