I got scammed the same way many people have by Tradesy, and of course I didn't start seeing all the reviews until it was too late. I bought a pair of "Chanel" boots on there.
I get them in the mail and at first glance I laughed! They had a fake Chanel logo GLUED ON with hot glue!! I was able to pick it off with no effort at all! Naturally I send it back as not being authentic.
After a few days of waiting I get an email saying that their Chanel "experts" examined it and confirmed its authenticity, so I was only issued a store credit (to which I had already prepared myself for after seeing everyone else's scathing reviews). I've already contacted them to tell them what I think of their "guarantee", and of course I used my credit towards other items on there that are probably fake too, but I took all my items off there and would rather sell them at a yard sale or donate to charity than let them get any kind of profit off my actually authentic items! Lesson learned. My advice to anyone using these sites is to stop.
Save up, buy a new item from the actual retailer as a reward for your hard work. That way you aren't buying some cheap knock - off at worst, or somebody's sloppy seconds at best.