One thing that bothers me is that I'm not sure of the actual mechanisms here.
If they're tracking my Google footprints, every damn random search might get put on my Permanent Record, and I have delved into some of the web's darkest underbellies in search of information on hundreds of subjects.
The most pervasive ads I got last week were from Adobe Creative Suites, and that was after I'd ordered the software for my daughter, so it seems that some vendors have direct input into these sites. Certainly I didn't have to google Adobe to know where to find the product.