Haven't been an Active™ JW for over 20 years, and I still can't bring myself to say "Bless you" when someone sneezes.
When I was a teenager, I found a German bible in the KH library, and found Acts 15:29 which used the word Geshundheit (good health to you). So I started using it instead of "Bless you". When an Elder™ reprimanded me for saying it, I told him (being a snotty teenager, naturally) that it was written in the German bible, so why should I not wish someone to have good health?? He didn't believe me, so I showed him. And since Acts 15:29 is so hugely important to the JW anti-blood transfusion dogma, how could he argue with that? The next time I checked, the German bible had mysteriously vanished.