#2: People who have no idea about the item they are selling and who can't be bothered doing a little basic researchTake for example the seller's description on this "Vintage Astoria electric guitar rare four string":
This is a very neat vintage four string Astoria electric guitar that is embossed made in Japan. I cannot find a serial number or model number anywhere. The tighteners at the end are very large compared to others I have seen and this seems rare because it is only four strings versus six. The neck on this guitar is in mint condition and the light maple wood is very modern. The body is in decent shape, though the enamel covering on the black part is scratched up pretty bad. The funky marble looking part is perfect. There is also one area pictured where the enamel is off completely. I don't know if it is enamel covering or a plastic of some sort, but it may be possible to just have that part redone and it would be mint again. The size and shape of this guitar is interesting too, as it seems much larger and heavier than regular electric guitars.Yes, I know it's very easy to mock who are not interested in the same things as we are and therefore lacking in key knowledge, but if you are selling something like this it might just help your auction if you found out about the existence of bass guitars.
Note also how the words "vintage" and "rare" are bandied about with reckless abandon and without any authority.