Seems to me the issue is courtesy. A timely response would be courteous and show there is interest in selling. An acknowledgment of receipt.
Seller Silence
On two occasions during the past month I have posted a question to a seller about whether the item still has a manufacturers warranty. One selling an Aurender N20 and the other a JVC NZ700 projector. Neither has responded even though it has been a few weeks.
There should be a way to leave seller feedback before a sale to inform potential buyers of this issue.