Ours is gross again.
I guess it gets built up after a few years... which is how long it's been since I last cleaned the thing. It was really bad...
Time Investment: Less than 10 Minutes
Materials: Grout Brush, scrubber, baking soda, cleaning cloth
Payoff: Maybe? If the dishes aren't noticeably cleaner (we'll see) maybe it will prevent leaking or gasket wear or something?
No one will ever notice except me and the dishwasher repairman, but it's now clean!