LOL at Listerine.
I was having a discussion with Triumph on this subject, but the Kanger Pro tank was the Atty I was having this particular problem with.
Kanger supply the replacement heads for their Protanks in an awfully pungent and stinking rubber tube/sleeve, (who knows quite what they were thinking there). Other manufacturers do the same, but supply their heads in a more "neutral" rubber sleeve. This literally contaminates the heads for the Protank and causes a very unpleasant taste indeed. I had to soak the heads in warm water for a couple of hours to remove the awful smell and taste these rubber tubes have caused.
Triumph informed me that Milton's steriliser is very useful in this regard.
Be careful cleaning or rinsing your CE5's in very hot or hot water however, it doesn't do the seals any good at all and it can cause the bonding for the metal collars on the top and base to fail. Then you'll be cursing them for leaking lol.
Listerine could potentially cause the bonding to break down as well, and I'd also question as to whether Listerine could even crack the plastic.
Hope the info helps.