Tonight I decided to try an experiment. I had a carto in a tank (with two holes) that I had been vaping for a few days. The juice I was vaping was 100% VG Highway from LF. It got to the point where it just tasted weird and burnt, so I decided to attempt to clean it out. First I just did some light cleaning of the inner-tube with a paperclip and some toilet paper, got some of that black gunk out (but not nearly all of it).
Then I decided to use the syringe method to plunge hot water in and out through the carto, followed by a vodka rinsing to infinitely speed up the drying process (only takes a few minuets to dry with when you do it this way with a Taryn spin and blowing out a few times). Only difference was that this carto has the holes for the tank that my other cartos did not have.
As I suspected, this cleaned out the carto infinitesimally better than cleaning without the holes, as with the regular method there is this 1/8" area on the bottom of the carto stuffing that is nearly impossible to clean due to it being slightly below the 'pole' that sticks out inside the cart (unless you have ripped a carto apart, you probably won't understand this). Well the additional holes make it so when cleaning, the entire stuffing is soaked and cleansed, not just the limited area near the hole in the middle (think path of least resistance).
I was able to remove every last bit of smell from my previous juice which had almost made the stuffing black. I proceeded to install a new flavor after the carto was properly dried and was surprised at how fresh the new juice tasted and had no signs of the previous flavor interfering.
So lesson of the day? Tank holes make for easy and more throughout cleaning when using the syringe method to for plunging hot water in/out of the carto! Heck, even vaping the carto with the open holes and no tank makes for better air-flow and seemed to be a more positive vaping experience. I might just poke holes in all my cartos even if they aren't going into a tank! Sure there may be leaking, but the longer condom that came with my cartos fits right over the holes I made for the tank, so this also makes for easy Taryn spin filling with no leaking.