Don't get burned by counterfeit perfume sellers.  There are many reputable sellers on Ebay.  Keep in mind if it seems too good to be true...it probably is.  Most countereit perfumes have the same designer names,  identical bottles, labels, boxes and are a similar fragrance! It can be difficult to tell the difference. Almost all major leading brands of perfumes are produced by the counterfeit market today. As a buyer you may never know, until you experience the actual fragrance in person.  You will realize it does not last as long or the texture is different than the original. Counterfeiting is a huge problem globally.  

20 Point Perfume Authenticity Checklist:
1) Confirm your seller is reputable - check feedback.
2) Check overall quality of product - look for original picures - not manufacturer website photos- if there are none ask the seller to post them for you and if they won't - don't bid.
3) Ask your seller plenty of questions you may have before you bid - if they do not answer you - don't bid. 
4) If your item is in the original box check for misspelling and make sure that the box looks like it is a normal good quality package with normal fold marks - it it should be embossed check for that .
5) Do your research - it is worth your time to look at the item in store first so you know what the original item is like if this is something you don't normally use - otherwise you may get the fake and be happy with it.
6) Bottle Shape. Check overall quality - height – width – basic shape and design.
7) Bottle Glass. Check overall quality – thickness - clarity – moulding marks.
8) Cap - make sure it is the correct shape/size and fits.
9) Sprayer Head - make sure it seems to work smoothly.
10) Sprayer Inner Tube. Check quality.
11) Main Bottle Label. Check for spelling errors.
12) Bottom Label. Check for the correct information.
13) Bar Code. Check if this is applicable.
14) Fragrance Colour. Check for murkiness, consistency of colour or if there is anything foreign floating in it.
15) Fragrance Oiliness. It should not be over oily.
16) Fragrance Smell  Make sure this is consistant with the fragrance you normally wear.
17) Fragrance Lasting time. Should last at least 2 to 3 hours or more. 
18) Skin Reactions. Watch for blemishes and rashes - if you normally do not have a reaction to your fragrance and do from this bottle - it could be fake.