The gap between these information types can be as thin as finding willing participants to match up two cookies on a Web page. With such a connection, suddenly behavioral information could be actively used by businesses to initiate contact with users through media such as snail mail, e-mail, and the telephone. Granted, this scenario is unlikely if advertisers and businesses know what's good for them. But there's a fine line between spammers and stalkers. Until consumers are granted restraining orders, there's been enough high-profile, egregious privacy violations in the past to keep everyone suspicious.
Behavioral data is certainly less subject to falsification than declared data.
But much of the logic behind profiling's value is rooted in the passive mindset of traditional media, such as television and radio. Passive TV viewers offer little information about their current interests. Thus a detailed profile about their past behavior greatly enhances any ad targeting potential. Contrast this with an active media characterized by user choice and interaction, such as the Internet. If you're trying to sell or brand yourself for auto insurance, search queries and Web pages about auto insurance shouldn't be the only place to promote your business online.