I'm not sure we're all on the same page here. Which type of cleaning are we talking about, because there are two totally different goals in "cleaning an atomizer".
The first type is getting rid of the e-liquid that gets in the wrong places in your atomizer. You can clean this out by blowing on it, setting it upside down overnight, or soaking it in just about anything. All of these things will clean out the atomizer.
The other type of cleaning is trying to get rid of the black, carbon-like "gunk" that builds up on the heating coil. This "gunk" is what the NU-Calgon Ice Machine Cleaner was used for. For the most part, Nu-Calgon works - but only if you exclusively use VG. For PG users, the only method that was found for getting rid of the gunk was to burn it off.
Exogenesis has some great posts on burning off the PG residue, if you're interested.