Found this tip on cleaning your bathtub jets from wikihow.com.
Run HOT water until it is about two inches above the hightest jets. Pour in about 1/2 cup of bleach and 1 Tablespoon of powdered dishwashing detergent.
Turn on the jets for 15 minutes
At the end of the 15 minutes turn off the jets and observe the gunk. Hey! They promised gunk. I got no gunk! Oh well. Drain tub.
Refill the tub with COLD water, and turn the jets back on for another 10 minutes to rinse all cleaner and residue from the jets..
At the end of the 10 minutes, empty the water from the tub, and clean the interior if it needs it.
I suppose I should be HAPPY that there was no gunk. That means I haven't been bathing in a dirty tub, right? I never really wanted a jetted tub for the very reason that the jets might be filled with hidden ickiness. Knowing an easy way to clean them occassionally makes me feel a tad better. Which is good, because I have become addicted to this here tub.