The “C” pattern will be crooked. Except for some newer patterns, like the “optic” or my new favorite “scarf print,” the tip of the horizontal “C” facing the other “C” should touch.
Also, the pattern should line up and start in the center of the front panel of the bag (same with the back panel). The center seam should go straight down through the middle of the CC’s, and the pattern should be aligned horizontally and vertically.
Also, the pattern should line up on any front or back pockets, so that it looks like there is no break in the pattern. (Note: Sometimes the pattern does not line up on side seams as this is nearly impossible to do.)
Sometimes the “CC” will actually be a “GG” – how much more obvious can you get! And no, this does not mean it’s a Gucci! (I’m not as familiar with Gucci products, but if someone is selling you a “COACH” bag which is imprinted with the letter “G” then logically it must be fake.)
The best way to tell is to go to the COACH website and look at the real thing, and then compare it to what you’re looking at on eBay and see if the pattern is different.