Its not just QVC, every website you visit puts cookies on your browser so it knows what may interest you and those ads will be catered to your interests.
Lately, if I happen to just look at an item on the QVC website, I receive emails stating that I left it behind. Very annoying. I don't like being spied on/followed around like that.
Get a good adblocker, it's worth every penny but there are also some that are free.
Last week I was at the hairdresser and we were talking about something, she put me under the dryer and I opened my phone to Facebook. . . the exact thing we had been discussing popped up!