Only the person selling the apples can send the apples request for mush, so if someones stupid enough to spam you, they'd be asking 10 mush for one of their apples .-.
Not exactly. Players will contact others all the time asking if they are selling or sometimes just skipping the asking part altogether and letting a member know how much they will pay for an apple, seeming to expect the player to just automatically sell to them without having previously contacted them to make some sort of deal or arrangement.. In this case, for 10 mushrooms. I have received such messages quite often in the past.