I used the original 808 cartomizers (with the white filling inside)
It does burn when it gets too dry. I tore one apart one day after cleaning it, and right in the middle, was a nice burn hole.
Cleaning, btw, is really easy. Boil them for 5, rinse, boil again, rinse. Blow them out, let them sit for a day to dry out. They take approximately 20 -25 drops to refill. They only need to sit for a few minutes to settle. You fill them till they look good and spongy moist, not soupy, but spongy. As long as you keep them wet, they will do you well, I used mine for over two months with no issue, could have kept on using them, but I wasn't digging that burn hole.
Best method is the second you get an "icky" taste, it means it's time to top them off.
It's why I switched over to the CE2's with no filling in it. Cleaner tasting, easier to clean (just a flush out with some warm/hot water, blow out, dry burn a couple of times, refill and move along) and, no burning.