I've never purchased any designer item thats not authentic. Whenever I want to buy something, I just go to that authorized store that sells it. I've just never thought about buying a designer item anywhere but from the authorized store.
As for how I feel about people carrying off not authentic goods and trying to pass it off as authentic, I think it's simply tacky. It's a misrepresentation of one's honesty. If one feels the need to purchase not authentic goods then you have to question yourself why you feel the need to mask yourself or dress a certain way even if it means purchasing a knock-off product. Bottom line is, it's dishonest. And individuals like these are only fooling themselves. Because those of us who have the real thing can distinguish the difference.