I like art and have bought few on ebay in the past, I am not a professional art person, but I have now understood few things, which would like to share ,to understand that what is advertised is correct, ask to see several photos of the painting including the signiture of artist if any and the back of the painting, if the painting is refered to as old, or pre 1900, then the back of the painting if canvas would nomally change color into a darker one due to dirt etc, similar with wood. should always try to look up the artist helpfull sites
artnet and findartinfo.com these are pay sites but will give info about the artist and can compare silmilarty of artwork and name of artist if exist, although some might not be registered their , but say 90% will be found.
Be carefull of items offered from the USA most of them I found copies or imtations and will then be hard to return as most of seller do not offer a return policy.Always ask the seller if they can accept to put a return policy at least 7 days, that will give you time to cheeck the item speacilly if paying big amounts. For decrative art this would not be needed .