Hi, I can relate somewhat....
Do you get enough water? Are you taking antihistamines?
What toothpaste do you use? Some are darned hard to get off the tongue.
After you brush, use a tongue scraper to get the rest off.
Do you drink coffee? I do, I also have great oral hygiene....but my tongue seems to be a bit "whitish". It's better now since using a tongue scraper. I'm using a whitening toothpaste, also a sensitive toothpaste, both from Aquafresh. Even with brushing and good rinsing, there's still some toothpaste residue/saliva that comes off when I scrape my tongue. Go figure.
quincy