1. Placement of The Monogram, And The Mnogram Itself - Louis Vuitton's monogram is an overlapping LV. The bottom ov the V shouldn't overlap the bottom ov the L. He is very precise about where he places them, because he loves symmetry. This is how a monogram should look:
3. Upside Down Monograms - There are some authentic LV's with upside down monograms. They use one piece of leather in some styles, so if there's no base to the purse, then one side will have the upside-down monograms, such as this bag:
5. Rivets - A real LV will have rivets both inside and out.
6. Straps - LV only uses leather straps; so watch out for vinyl!
7. Patches - A lot of the older fakes have patches on both the outside and inside, but authentic vintage LV bags will sometimes have a patch on the outside for custom embroidering of initials. Some recent LV bags also have patches inside.
This definitely isn't all that separates real LV from fake, but it's some of the typical, easy-to-spot stuff! I hope this helps somebody out, and keeps them from making the big mistake of buying a fake.