I assume that the practice of real estate is the same or very similar across the country.
When a property is listed for sale it is presumed that the seller wants to sell.
When an offer is presented on a property for sale it is presumed that the buyer wants to buy.
The sellers agent's acts are dictated by the seller.
The buyers agent's acts are dictated by the buyer.
Whatever the sellers asking price and whatever the buyers offering price, each agent is representing their client's interest with the goal of finding terms and conditions acceptable to them (client).
There is no requirement for the seller to accept or counter an offer that is less than the asking price.
There is no requirement for the seller to accept or counter a full price offer if the terms and conditions of the offer are unacceptable to the seller.
Neither seller nor buyer are bound by any standard of ethics.
Real estate agents are bound by standards of ethics.
What you decide to do is what you decide to do.
Hope this information is helpful.
All the best,