You've got to see the history to all this atty cleaning thing really.
Stubborn stains need harsh measures, so many people tried many things,
& it got ramped up to using 'ice cleaner' (50% or so phosphoric acid),
which seemed to work for some people, where nothing else would.
We're mainly talking about attys that had been used long and heavy,
and milder regimes no longer work too well (or at all).
Initially coke soaks, IPA, ethanol, lemon juice etc, etc do work OK,
but later (if you're not in the 'chuck it out' faction), then you might
try the harsher regimes
Personally I use the 'dry burn + H2O2' method, since the red hot coil
carbonifies & 'smokes off' (90%?) of the burnt-on juice,
then any hard crud left behind gets broken up by the H2O2 'fizz' and
breaks away with a rinse.
So it's case of whatever works...
afaik the atty case is stainless steel, so doesn't get corroded,
the metal with is pure nickel, the only thing that might suffer
would be the silicone grommets (they dissolve in strong sulphuric),
but they seen to survive H3PO4 completely.
The element is Nichrome which is totally OK with this too.
Also the point is to rinse/soak any chemical completely out before
using the atty to vape with
(which is really the point of this latter test....I'm getting to it, just gearing up fully).
And yes, some (cheaper) atty paint jobs can be peeled with strong H3PO4,
but most are OK.