First of all, I have zero confidence in any field applied coating, may give you a year longer life than no coating at all.
Factory applied coatings are much better.
It is going to depend on the type of coating being used.
"e-coat" sounds like carrier lingo and a few years back they were coating them with 'electro-fin' and it was black.
"heresite" is a type of phenolic coating that is used it is reddish brown, cannot miss it
"adsil" is a clear coating that is used, so far I like its performance. One way of telling with adsil is there will be a label on it saying adsil or microgaurd certifying that it has been coated and giving warnings about certain cleaning methods not to be used.
So for a definitive method of telling if it is coated or not, talk to the people who make the coating you want used. Is e-coat a generic term or a tradename on your side pof the atlantic.
You must have liked seeing Brazil lose

good going Team NED
The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install