omg I wouldn't even think of that!
When I was first starting on ebay, I asked one seller (a very reputable one, but I didn't know that then, I was a newbie
) where they bought the bag, because I read in one guide it's good to ask that, because some people don't know that for instant LV doesn't have an outlet etc., so you might "catch" them lying. I know today that asking a seller where they bought the bag makes absolutely no sense, because if they want to trick you they will, they will give you the "right" info, fake the receipt or use the original one to sell a fake bag etc., so I never ask.
You are right, I understand now. It's good that you listen to your instincts. I can't believe what some people are willing to do...