I absolutely rinse them out with water after they have soaked. For darker strong juices I first rinse them to get the intial old juice out, then soak them in vodka, then flush them with bastor in the vodka, the rinse them out for a couple of minutes in hot water. Some dark juices are just not Carto friendly when it comes cleaning. I stopped even attempting to clean those months ago, instead I just keep topping off until I toss them.
I only clean carts that I have been using light juices in like Wow Peppermint, 555, RY4, Wowboy, Grape, Razz Wow, Wow Nuport, etc.
If you find there is still too much water in the cartos for whatever reason, you could always let them sit for 30 minutes or so mouth piece end down, then try re-spinning them. Now some will tell you they have great luck with boiling them and baking them, which very well may work for them, but when I tried a dozen times or so I found I killed the bulk of the Cartos.
A little residual water in the Carto will only result in the first refill having a little bit of an off taste for the first 10 minutes of vaping. At most there maybe 1 or 2 drops of residual water left in the polyfill after being spun out mixed in with 20+ drops of juice after refilling it dissipates into vapor quickly.
