I'm one of those who have no trouble with Clearomizers, XL or Regular, 2.8 or 3.0 ohms on 4.27 to 4.4Volts, juice is pretty much 70%PG to 30%VG. I only vape clear or nearly clear e-liquids, typically tobacco or minty juices. Brand new out of the package, I simply fill them with a regular syringe needle, nearly full, not all the way full - I don't know why, but if I stuff it full of juice to where it runs over into the tube and I have to blow it out, it doesn't seem to wick right for a few vapes. Anyway, after filling nearly full, then I drop a couple of drops straight down into the coil and let my PV sit on its side for a couple of minutes or so, letting the wick get nicely saturated and do it's wicking thing. Pick it up, vape, no problem. I don't ever let it go dry, that's one thing I love about clearomizers, I can see when it's getting low. Fill 'er back up, don't have to do an extra dripping thing on the coil this time, just continue vaping.
For me, any dark juice or very sweet juice or sorts of chocolately juice burns onto the coil of any atty/carto and is burny-tasting pretty quickly. Also found that any all-VG or high % VG juice never wicked properly in any atty or carto and so for me, has to be dripped. Gave up on screwing around with all those types months ago. Sticking with what works now, lol.
Cheers y'all,
SteelJan