I'm mostly a seller, and though they do get annoying after answering 20 different emails, I understand. If you're spending that much on a bag that you can't see or touch IRL, an assurance may make the buyer more comfortable. I've seen quite a few seller's lately with something similar to "questions on authenticity will not be entertained". To me, that seems rude. If I'm going to drop upwards of $500 (and more likely over $1000) on a bag that is final sale, online, I think a seller can at least be accomodating enough to send me a polite response. I would never bid on a bag, even if I knew it was authentic, if that was the seller's attitude.