Some wipe out the bowl with a paper towel or some such after each bowl so "cake" doesn't form. I clean my pipes each Sunday, briars, cobs and meers. I am careful not to let any cake form and gently scrape the inside of the meer bowl each cleaning. I do not scrape the meerschaum surface itself, it will be black from the tars and other residues of the tobacco.
If you are just starting with meers I'd suggest wiping the bowl every smoke or so. If you notice any cake starting to form remove only to the meer (If you start to see a lighter colored surface when you ream stop, you've gone a wee bit too far and any further will damage the bowl surface.) Cake will slow, maybe prevent, the absorption and the coloring process. Alcohol will remove the stuff you want for coloring. A quick wipe with a paper towel should keep the bowl clean and smooth to the touch. I'd stay away from the alcohol, can't say why, just would as it isn't needed.