Don't count on being able to clean stuffing-type cartos. They are meant to be disposable. Some people succeed at cleaning and drying them and some do not. Don't count on yourself being able to do it unless you have already done it.
I also recommend you not use cartos to test juices. If you have a KR808D-1 (or Vapor4Life, Bloogplanet, V2, Smoketip, or other KR808D-1 threaded model) stick a standard resistance DSE901 atty on it for testing juices. You can use a drip tip if you hav manual
batteries (just don't drip a lot in the atty since KR808D-1 manuals still have a hole in the end). If you have auto
batteries use carts or buy a manual battery for testing juices. A KR808D-2 can use a DSE901 atty w/ a D2-to-D1 adapter from LeCig.
I only put juices I like in cartos - juices I want to vape for the life of the carto.