Ebay is a global marketplace with millions of buyers and sellers around the world. It is a great place to find both vintage and second hand pieces. However if you are in the market for luxury clothing and accessories you, unlike when shopping on Vestiaire, you need to do the authentication and quality control on your own.
This makes it even more important to pay attention to details and request more images of the item if you are feeling iffy about the authenticity or condition of the item. Have a look at the seller or store reviews and establish a good dialogue with the seller in question. Many of the sellers of luxury vintage or second hand items have instagrams as well, so be sure to check that out as well to get a feel for the seller.
Check out this post for in-depth instructions and things to keep in mind to score major vintage and premium second hand deals on Ebay.
Thethriftylondoner have created a buying guide for scoring great vintage pieces on Ebay, check it out.
Ebay also have their own buying guides, check out the one for fashion here.