I've had mixed luck with AliExpress. I ordered a leather bag (which I knew was PU), and when it showed up, the print on the PU was already scuffed. On the first trip, the over the shoulder strap buckles came off, and by the end of the trip, one of the straps was hanging on by a thread. I also have a pair of Tom Ford Wayfairer style sunglasses though that look great, came with replica packaging and everything, and they were cheap enough that I let the kids wear them if they want!
My rule of thumb is now that if it looks simple, it's probably easy to replicate and will be a good quality product (most sunglasses, belts, cufflinks, etc.), but as soon as you're looking for something more complicated (bags, watches, etc.) you have to be a lot more careful where you buy from.