I'm not sure why some are so defensive on this. Some folks say yes, some say no. As a pipe maker of over 2,700 pipes I've did a bit of research myself. I know dry wood is good for pipes, no one makes a pipe with wet wood, we all have our drying methods. Dry wood and water don't seem to mix. I know many pipe makers use shellac as a finish, shellac and water don't mix, just try and set a wet glass on a table (finished with shellac) without a coaster and see. Is there moisture in smoking? Sure there is but that's not the same as flushing it with water. I've seen first hand how moisture can warp a mortise, a chamber and even crack both. From my experience I'm going to keep water away from my pipes as best I can and never flush them or reccomend it. Bottom line we own our pipes we can flush them with hot water, hot coco or hot sauce or what ever else we want, but I would never reccomend it.
As for alcohol in a mouthpiece, I've been doing it for decades and I've never noticed any adverse effects. I'm not saying it's right, I've just never noticed and I'll results. What is my recommendation worth?, exactly what you paid for it