I usually consider myself reasonably savvy when it comes to internet stuff. I even used to work in ecommerce, but apparently I was there before the days of retargeting. Essentially, you start out at website A, then meander over to B and maybe even C, before retargeting companies bring you back around to the site you were at originally.
Brilliant, I'd say! The actual conversion rate of people doing something the first time they're at your site is very low. But of course it goes up the more times they 'visit.' So if retargeting advertising turns their first visit into their first two or three, you're making progress toward getting their business, right?
I would say I didn't like the idea, but it must be pretty subtle if I've never noticed it before, right? That's my guess anyway. It beats doubting my own observation skills ;)