The "all cotton" Aspire K1 BVC I just washed a couple of minutes under hot tap water in an attempt to get rid of the ugly taste.
As mentioned I did not dry it. I just blew out the water befor reinstalling it into the K1.
Still have to try if presoaking a fresh "all cotton" BVC in 70% ethanol works to get rid of this taste.
With my modified K1 BVC I just remove the old cotton wick, rinse the coil head in hot tap water and blow it out briefly.
Then I make I dry burn and rewick it with cotton. This way it tastes like a new one.
Usually, I prepare rewicked coils in advance and soak them at least a couple of hours in PG/VG.
I have the impression that it's better to soak the fresh cotton wicks for some time in PG/VG before I use them.
Therefore I always have a couple of rewicked coils presoaked in PG/VG without flavour in a small minigrip bag. Often they sit there for weeks.
Rewicking the coils 3-4 times usually works without problems.
With my non-NET liquids I change the cotton wick every 1-2 weeks. So one coil usually lasts for at least one month.
You might want to try soaking in near boiling water for several hours, it usually breaks up the gunk in mine.