Your basic question--what is a pipe sweetener? It's an alcohol based solvent (denatured, as noted above,) with a few flavoring additives, such as mint, etc. The solvent is intended to dissolve the gunk in your pipe, and the sweetener is intended to remain behind as a residue, thereby masking any unpleasant taste remaining in the pipe.
My advice is the same as others: use a food grade solvent such as Everclear. It being 190 Proof, i.e., 95% alcohol, its dissolving power will be greater. When you're satisfied that your pipe is clean, make one more pass with the liquors mentioned above. Some go for bourbon, others prefer irish, scotch, a certain brand of rum, etc. Pick your own. The main thing is to clean the pipe, leaving behind a nice fresh scent. How often should you do this? As often as necessary. I'm a clean freak, and I like my pipes to be spotlessly clean. Others clean after every 10 smokes, and the list goes on. You'll know when the pipe is beginning to develop an unpleasant taste, then it's time to break out the alcohol.
My advice is the same as others: use a food grade solvent such as Everclear. It being 190 Proof, i.e., 95% alcohol, its dissolving power will be greater. When you're satisfied that your pipe is clean, make one more pass with the liquors mentioned above. Some go for bourbon, others prefer irish, scotch, a certain brand of rum, etc. Pick your own. The main thing is to clean the pipe, leaving behind a nice fresh scent. How often should you do this? As often as necessary. I'm a clean freak, and I like my pipes to be spotlessly clean. Others clean after every 10 smokes, and the list goes on. You'll know when the pipe is beginning to develop an unpleasant taste, then it's time to break out the alcohol.