Some juices flavor will linger in a carto even after you clean it. I recommend using an atty to test juices, put a drip tip on the Atty and drip a few drops of juice directly onto the atomizer. Then when you know you like a juice, fill a carto. It will help save juice and also not waste cartos, also you wont have to keep cleaning cartos so you can put in a different juice. I designate one carto to each juice I vape and only refill it with that juice. If you use them correctly and don't let them get dry, they can last a few weeks and not necessarily have to clean them. I never clean my cartos, but some people do. I find that some cartos won't work as well after they have been cleaned. Either they won't hold as much juice or they wont wick as well. But thats up to you if you want to clean them. I would def use an atty to test your juice though, that will cut down cleanIng your cartos over and over. A regular carto normally def won't work as well if they are cleaned constantly