I would have to agree with @Evan Saltis , I've put a few best offers in and they were rejected right up to $1 less than the offering price. It's a scheme for better exposure. Some don't do it for that and actually entertain offers or a back and forth.
No doubt. This tactic is so distasteful it makes me not want to buy from a seller that does it though.
I have a price set already in my mind when I go in to any transaction and many things can ruin it, even if the seller can meet that price. It's not being snobby, it's just I'd rather not give my business to someone who thinks they are above you or snotty or (insert whatever your pet peeve is here). Likewise when you're selling. I have a price in mind going in to the transaction but we all know that if someone is pleasant or a repeat customer, that price can be changed, and should be for great customers.