Throughout my time searching through ebay, ive noticed quite a significant number of fake guess bags getting around - this makes me so mad! I work with guess bags, so i have quite and eye for picking out the fakes (which i do report straight to ebay!!), but to the un-suspecting average ebayer, picking up the signs of a fake guess bag can be very hard to do! (I hate the thought of people being ripped off like this). So, heres some things to look out for when purchasing authentic guess bags:

1. Authenic guess bags will have a metal 'guess' badge inside of the bag

2. 99% of the time, authenic guess bags will never just have a 'G' buckle on it - they always have 'Guess' written on the fabric, or buckle itself (except in the very rare case such as the Ginger Cat range - thus refer to the metal badge)

3. If being advertised as BNWT, always make sure its the original Marciano tag - not just a plain made up one

4. If being advertised as BNWT with stuffing still in bag, it should have the guess logo paper in it - not just normal tissue paper / news paper

5. Fake guess bags will usually have fairly dull, cheap looking brassy hardware on it, rather than a shiny gold or silver like on the originals

Here's two comparison pictures of a fake (picture 1) and a Genuine guess bag with its metal badge (picture 2)

1)               2) 

I hope this helps! Good luck!