Maybe some of you veterans can help me. I am using a standard pipe cleaner. I pinch between my thumb an index finger on the top end. I gently push it down the stem and into the chamber and move it back and forth several times. I then turn it around and place the other end in and do the same. I seem to be getting a strange smell and dark stains on my thumb and index finger. What am I doing wrong? Does this happen to everyone?