Good question. Technically, if it is stolen, and you don't know that it is, I don't believe you can get in trouble for receiving stolen property. I would, however cover your ass and check the serial if you plan on buying and you suspect it may be stolen.
How do you check the serial number? Is there a "GunFax" type program or something?
Kyle
Girlscouts? Hmmm, I don't know... I think it's kinda dangerous to teach young girls self esteem and leadership skills.