This has been brought up a few times before actually. And you are correct, that the seller should have asked your permission before using the picture.
I assume that the seller does not have a digital camera, (or is just plain lazy), hence the reason for "stealing" your picture. The other reason could be that this seller is a scam artist, and just grabbed a picture of something he thought he could "sell" quickly and easily. You might want to contact Audiogon about this, just in case the later happens to be the situation in this case. (And since Audiogon is rather a stickler about giving credit for "intellectual property", and since it is your picture, they should take action in this case.)
My two cents worth.
I assume that the seller does not have a digital camera, (or is just plain lazy), hence the reason for "stealing" your picture. The other reason could be that this seller is a scam artist, and just grabbed a picture of something he thought he could "sell" quickly and easily. You might want to contact Audiogon about this, just in case the later happens to be the situation in this case. (And since Audiogon is rather a stickler about giving credit for "intellectual property", and since it is your picture, they should take action in this case.)
My two cents worth.