When you decline, you are asked to select a reason. One of the selectable reasons is something along the lines of "not a good fit" which I always assumed was due to people asking for things clearly indicated as not feasible within the listing itself. For example in one of my listings I clearly state that "you will need a car to get here" but I got an inquiry asking about public transportation. My place is in the woods in the middle of nowhere so I assumed the person just didn't read the listing, so I declined it with the "not a good fit" option. Does replying with such a reason get a black mark?
Sometimes I just let the inquiry expire without declining it, after some correspondence with the person where we agree the booking wouldn't be right for them (because of price, dates, number of people, etc.) I wonder if this earns a black mark too?