Any adverts I see that relate to learning 'secrets' of how to do X (in which X is lose weight, get rid of stretch marks, yada yada yada) I consider as bait for spyware-naive web browsers.

In all honesty, I don't find tailored advertising that irritating. On facebook, some adverts relate to things useful to me owing to the information I have on my profile, and I've actually come across a couple of good veterinary and travel sites that way. My father works with several businesses who employ social media advertising and it makes a huge difference - it's equivalent to having a store-front in some global shopping mall!

I am terrible for browsing clothing websites, however, and the cookies tend to follow me around for several weeks, just to torture me with images of that dress that would-look-oh-so-lovely-but-is-oh-so-pricey...