Just an extra tip.. Q-tips work great to clean out the empty cart of juice and gunk before re-stuffing. The wetness in the cart absorbs better into the cotton than tissue or papertowel.
Spikey's right...q-tips do work better.
Unfortunately for me, I used the last of my q-tips after my shower the other day and haven't gotten to the store to buy more so I did the paper-towel trick.
For the mouthpieces, which can also get quite a bit of fluid in them, you can use q-tips as well...just work them around the sides and make sure to mop up the bottom near the air-hole.