Nina came off as the idiot in their exchange. It was perfectly fine for her to not like the aesthetic of the design. But she also had this snooty superior "there was nothing of Paris" argument, which was totally untrue. Maybe it wasn't NINA'S version of Paris, but it certainly was A legit version of Paris.
I could totally see the graffiti and bill-posting idea in Patricia's design. I don't think that it was immediately reminiscent of Paris, but that is what she saw there and that is what inspired her.
I wonder if she'd had Berlin and done a similar design (after seeing the artwork on the Berlin Wall), if Nina would have reacted with the same tunnelvision. The stuff on the wall in part of the cliched obvious image of Berlin, so Nina would have "known" that Berlin. But she doesn't "know" that aspect of Paris.