Unfortunately, Roth is right. If you clean the pipe right after it has completely cooled down from the smoke, you will get all the residues out without a lot of effort. If you let it dry, it is much harder to get it out. However, I have been guilty, too, of going to sleep after the last smoke of the day and letting the pipe cool and dry until I clean it the next day, but if I clean it right after smoking the next time, I can see, that a lot more dirt, than from one smoke is coming out. That's why I now, if I really cannot clean the pipe right away, clean it with alcohol dipped cleaners as soon as I have time, although I normally do not clean with alcohol very often.
Kind regards,
Peter