As someone who works at a second-hand store, this is a very rude thing to do, and I would politely tell you to leave if you continued to do so. Poaching buys is pretty low: while you just want a game, we're fronting all the costs to bring that game to you. Plus, you don't get our 7-day money back guarantee! Likewise, selling things to other people inside the store or just outside will get you asked to leave.
In this case, both people came in for one thing. One person came in to sell a game, the other came in to buy that particular game. You can tell them to leave all you want... they have no further business there that day anyway... unless it was to buy something else from you. Now, somebody standing outside trying to hawk games to customers coming in... that's a different story.
I've been surfing the web for at least 12 years. I've probably hit dozens of ad-infested pages per day during that time. I've probably seen tens, if not hundreds, of thousands of ads.
I can't remember a single time when I actually purchased something because of a web page ad.
I may have been influenced a bit due to a few of them, but actual purchase that I wouldn't have made otherwise? If so I have forgotten about it.
If you have been influenced by advertising, then the advertising has worked, plain and simple. It may have been something that you would purchase anyhow, but how would you know you wanted that specific brand, or its particular strengths versus it's competitors? Now, you may have other factors that may influence you to NOT chose a particular product, (obnoxious advertising being one of those).
Term, holidays, term, holidays, till we leave school, and then work, work, work till we die. -- C.S. Lewis