I only started getting into ebay a few months back in order to sell things that other people could make use of instead of throwing it away and wasting it. Although the idea of an online auction place is ingenuis, and a lot of people use this marketplace in good faith, there is unfortunately a lot of people who misuse the concept. It annoys me highly how many fakes of designer bags are out there, and how many people actually bid for these! It is always possible to pick up a bargain on ebay, and here are some of the basic things I would always check before over-paying for an item that is essentially not worth anything.
You've found a bag you like and want to buy it. You've seen the listing and it looks could. However make sure you inspect both the interior and exterior before you buy the item. Ask the seller questions. Often communication with the seller reveals a lot about them. See if they give you straight forward answers or not.
In addition here are some basic things you should definitely check:
Ensure that metallic logo tags, lining or any other labels are not glued on. These should be stiched on.
Look at the symmetry of the design pattern, these should be in line. If they are even slightly tilted you can be sure it's not real.
Have a look at the interior; Even though the outside may look immaculate on a 'good' fake, the inside lining can give it away by poor quality lining. You often get bags where the inside lining is 'pulled' in places. Hardly good quality and hence fake. A designer bag is expensive for a reason, they have flawless perfection and quality and the inside stiching should be perfect.
As for the outside check for any loose or missing stitches. The color of the thread should match the main color of the bag and the stitches should be evenly spaced. I've seen some Brown Zucca bags with white stitching on ebay which are marketed as authentic and still get bids!
Feel the material. If it's overly stiff or overly soft chances are good it's fake.
Ask about the source of the bag. Was it a gift? A lot of sellers will avoid the question saying it was a gift in order to hide the true source. Ask where it was purchased, ask for the receipt. If they don't have the receipt then stores usually have all purchasing in the computer system so they can easily get hold of a copy if they wanted to.
KNOW YOUR BAGS. If you're not sure about the collection, have a look in the stores. A lot of designer items have serial numbers which should be the same for a particular design, compare these in store. Just because you are given a serial number does not gurantee it's authenticy-they could be random numbers. Make sure you do your homework.
Also just because sellers offer authenticy card or hologram labels it DOES NOT PROVE the bags authenticy-these can easily be made.
There is a big market for fake Louis Vuitton bags, but it's not too difficult to spot a fake if you look closely. The colors usually give it away. If you see an item that you like and not sure about, visit the official websites and compare the items. They can be more or less the same looks wise on the outside, but fakes usually have the wrong design inside.
Also surely the price gives it away. Why why why would anyone who purchased a bag for £400-£2000 sell it on ebay for £20?? And ever wondered why people sell BRAND NEW bags for a fraction of their cost? And not only one, but zillion of them??
Fundamentally good common sense is the key. Always be sceptical, expect the worse because unfortunately there is a huge market of fakes out there. If it's too good to be true it's not true.