Some of us are far more particular and sensitive to "ghosting" than others. Likewise, if you have a number of pipes, so you aren't repeatedly smoking a blend in one pipe, it may not matter as much. Also, ghosting may depend on caking. Some of us aren't cake builders, scoop and wipe out a pipe after every use, just relying on a thin layer of carbon; my pipes bought new thirty-forty years ago like this method very much. No cake means little or no ghosting with most blends. A few blends, like U.K. Lake District "Lakeland" blends, particular ones with specific ingredients, will ghost anything, so if you get into those, just smoke them in designated pipes marked with heavy day-glo duct tape (just kidding) or cobs.