If you're on a tight budget and can't afford to get new cartos on a weekly basis, there are ways to clean them that aren't totally useless.
for regular "fluff filled" cartos, I soak them in grain alcohol for half hour , blow them out , rinse with hot water and blow out again, then set them up to dry one day prior to refilling.
for ceramic cartos, you can't really clean them just flush them. I do it with alcohol only, no water.They have video tht shows someone taking them apart but I haven't been able to get the sheath off the base on mine so gave up on it. I use the syringe to suck the liquid out of them , alcohol included , then blow them out till I want to pass out (hard to get all the liquid out of these) and dry burn a couple times before refilling. Get some residual alcohol, but then some liquids have alcohol in them anyway so it must be ok to some small degree.
for clearos, I simply take them apart, rinse in hot water swish in alcohol , blot dry and put back together. I like how easy it s to thoroughly clean these.
I have some ceramic cartos that are almost two months old that still work nicely. But when it starts not producing enough vapor , or the coil looks too black I toss em. Of the four packs of cartos I have bought since november, I have only had to throw three away. Though one of them is beginning to hit that point of no return so it might be four soon.
All in all, if you can afford it, get new ones weekly, if you can't , at least rinse em once a week and let them dry for a day.