Scary looking nasty in the bottom of each of those chambers. Although I'm somewhat guilty of neglect at times, I'll try to at least prep for winter, and clean out my units of all visible gunk.
These days I purchase spare parts well in advance of the manufacturer's planned obsolescence of their unit so I can fix my grill rather than having to throw it away. One of the parts that I find degrades the easiest is the diffuser plate above the gas burner, and the gas burner itself. I currently have this Charmglow:
... and just yesterday my wife and I gave it a through cleaning and parts replacement (only need a diffuser this time). It might not be perfectly pretty, but it sure did work well with the pizzas we did last night.
We live in a rather rural/mountainous environment, and I almost am never without my weapon. I even walk down to the mailbox, and do all of my back deck socializing with it within arms reach.