The initial thing to be aware of is that the bags are dark but not all that glossy in terms of the leather that they use. Like other expensive brands, the leather utilized is soft and fairly thin whilst cheap fakes use a thinker and tougher leather making it much cheaper.
The next thing on your list of characteristics to look for is the linning. If it is a nice soft cotton then that's a very good sign. The fakes tend to use a cheap synthetic material which is rough. Some people don't mind buying a fake as long as it's cheap but if you're paying a lot of money for junk that you're going to be really mad when you find out the truth.
You should also pay close attention to the stitching that has been used. The cheap fakes use a rough and uneven stitching whilst Juicy Couture uses a fine quality stitching. They take their time when making a bag and it really shows in the finish.
As they say, if it seems too good to be true it usually is. Juicy Couture is a fairly pricey brand and will never be sold at dirt cheap prices (unless it's used and worn in which case it's going to be cheaper than the retail price).
When buying from an online auction site you should have a look at the seller's feedback and don't bid on anything from a less-than-desirable seller. If there are hardly any photos of the items this should be a warning sign. Ask them for more photographs, especially focusing on the detailing. If the seller won't provide extra photos or they don't reply to your question then proceed with caution.
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