My most received question asked is variations of the infamous "Is it still available?". In my experience, 1 out of 10 is a sincere buyer. Perhaps another would thank you for your reply meanwhile considering. The other 8 vanished into thin air. Those are half hearted, indecisive or probably found a better deal so it is up to you want to reply or not. Most of my successful deals starts with price nego/offer button or deal location/timing. Maybe 1% from still availableans.
Now that 1 sincere buyer can either be a steady buyer and damn smooth deal OR slowly reveal their intentions like deal at their location, lowering price further than what you already gave them, sometimes even after joining the % off sale event, being lowest priced amongst other sellers. All these won't be asked in the beginning of the conversation. There will be a few questions asked with delays which are already answered in description and images before they get to the true objective, nego price

As I've mentioned, this is totally cool if the buyer had read description or begin with nego price, use the offer button. Instead some like to annoy people by first getting their attention and proceed in a backwards manner. Asking answered questions, agreed to deal, fixed time and location then proceed to nego price.
Sometimes I wonder why don't they just get brand new from shopping apps if so doubtful, get some coupons, coins, shopback to sweeten the deal. If not satisfied, return it. When you've already listed the condition of the item and included as many images you can possibly uploaded, people can still ask about the condition. Unless buyer check on the spot, otherwise whatever words from seller means nothing.