This is completely false for the free market. A trade in the free market is always a win-win. It is the definition of the free market. If a trade is not win-win, it will not be completed.
There will always be cases of seller cheating the buyer by selling crappy products and services.
Or there will be cases called "externality" where factory owners and buyer of their products area happy with the price but do not have to pay the cost of polluting the area.