I used to use Whiskey to clean mine, then switched to Everclear.
You shouldn’t scrape the inside chamber, you want a “cake’ layer to form. It insulates the pipe, and protects it from possible burn through.
As for how often to clean, after every smoke. I run one or two dry pipe cleaners down the stem and shank into the chamber. Gets excess moisture out, then take one or two more dry cleaners and bend them in half. Then gently wipe the inside of the chamber out ( like your dusting ) If you are doing it hard, it will take longer for cake to form.
Deep cleaning, where I take them apart. Clean everything with Everclear, and ream the chamber. That depends on how much use that particular pipe gets, but typically every 6-8 months.
One word of caution, do not let the booze get on the outside of the bowl. It will discolor and strip the finish off. Just a heads up!
HTH
Chris