If you're refilling yourself, it sounds like you're overfilling your carto. When done, it should look kind of like a slushie, not completely soaked.
Blowing through the carto and wiping the battery end after filling usually takes care of that very nicely, but when I used cartos I tried for the minimal amount blown out (none if I could manage it). Anything that hits the wiping cloth is just a waste.
We've all gotten the drop, or small mouthful, of
juice. Spit out small mouthfuls, but drops won't hurt you if you accidentally swallow it.