That's the seasoning! LOL.....
Before using the the racks on each smoke, I spray 'em good with Pam. A quick hot water soak in the sink after wards and they are clean. Ultra Soap is antibiotic and dilutes those fats off. Then if you are still worried you can use the dishwasher on super hot scald you skin off. But I usually just let 'em soak and that stuff comes right off easily.
The water pan, when you are finished get an SOS and get shiny clean, wrap it inside and out in alum. foil. And life is easy. I seasoned my originally and so far after over a couple a dozen smokes it comes clean easily, (its stainless steel too). That Ultra is good stuff. When I saw 'em cleaning the oil off the birds in Grand Isle, I was impressed, still am.
I don't think my pipe pits have ever been cleaned. I nearly ran an employee off for blasting my big one. He was so proud of himself for doing it, getting all that old black stuff off. Funny now, wasn't so much back then.
I don't get anal about clean, the USDA nor the Health dept check me.