In my experience, people with super clean desks aren't consistently productive. Garbage or dirty dishes are the byproducts of computer work. If you aren't neglecting the cleanup sometimes, you probably aren't working that hard.
I prefer cleaning things up(both digital and physical) at the end of the day, to relieve my mind that I'm "done" with work and move on to other things. I found it's horrible to wake up, sitting at your desk and the first thing you see is all your piles of crap that your postpone the night before.
For more general desk junk buildup I have to neaten it up every week or two or it too will become a distraction.
I can't just walk off without mentioning the importance of a tactical housecat capable of pre-cleaning the dishes so as to not attract vermin- the plus side being if said housecat is a subpar dishwasher, they're all too willing to take care of any enterprising houseflies bound for a meal.
Both extremes are not very productive. But a person doing actual work might have more than just a completely empty desk. What about a cup of coffee, or a notepad, or a small whiteboard, or a reference manual? Because if everything you might need is on your pc and you don't leverage your immediate three dimensional reality, you're not at peak productivity. A manual on the desk is "better" than a PDF on a second workspace.
maintenance > cleanup.
Though one things missing from all the fluff about how things look is how things feel. Having a foot rest, or something I can put my feed against is super important to getting things done and not having my body feel like crap at the end of the day.