Although more mainstream adware companies are working to ensure that their software is installed with users' knowledge, smaller companies are secretly installing ad-serving programs that are more pernicious and difficult to remove than ever, according to the second-quarter "State of Spyware" report by anti-spyware software marketer Webroot, MediaPost reports. About 50 percent of consumer computers evaluated by Webroot contained adware in 2Q05 - down from 64 percent in 1Q05 and 73 percent in 4Q04.

Some 83 percent of consumer computers had spyware, adware, system monitors, Trojans or cookies, down from 88 percent in the first quarter and 92 percent in the last quarter of 2004, according to the report. Some 73 percent of consumer computers contained cookies, which online advertisers and consumers tend to view very differently.

"Many consumers have indicated that any type of application placed on their PC without their knowledge is spyware," stated the report. Of course, marketers would point out that cookies are not applications.