Sorry, dear, I did, that is why I posted my answer. I have done all kinds of tests with NEOs since I am using them from day one...
I have indeed experienced what you mention with all my CE4+ but the only time I had this issue with NEOs was when I used VG e-liquids in them. With Janty PG e-liquids, my coils remain white - I can even post a pic from the one I am using right now (2 months old) and I swear, I haven't cleaned it...
But, as I said, I keep losing my puromizers from instant deaths within a month or a couple of months, so maybe that is the reason they remain clean, although I vape 3-4ml of Janty's PG e-liquids per day with them in the meantime.