doubleclick is one of the largest data collecting corporations on the web. They have TONS of information about almost everyone, all from cookies.
“DoubleClick is sometimes linked with the controversy over spyware because browser cookies are set to track users as they travel from website to website and record what commercial advertisements they view and select while browsing. However, the company maintains that it is important to understand the difference between DoubleClick’s ad serving tags and the spyware/adware companies.” (from http://googlesystem.blogspot.com/2007/04/google-buys-doubleclick.html )
Now Google has bought doubleclick. So, if doubleclick is evil or close to it, then how is Google’s “don’t be evil” policy going to hold up? Hmmm.
I’ll leave you with one more quote from the above-referenced article:
“I don’t know if there’s a single ad blocker or cookie filtering program that doesn’t include doubleclick.net in its black list”