I hereby confess to using a neti pot over the kitchen sink. (1) The salt and the measuring cup are already there, as is the dish soap. (2) The bathroom sink is tiny, increasing the odds of, um, spillage. (3) It's just the cats and I, and the cats don't care. (4) Saliva can't be any more germy than chicken blood. That said, I would never, ever spit in someone else's kitchen sink.
The original kitchen sink was porcelain. Years of scrubbing with Comet removed the glaze, leaving it prone to staining, which meant more Comet or Clorox, which removed more glaze . . .
Current sink is stainless steel. I must say, the dishwasher makes a lot more noise with the stainless, perhaps because the shape and material amplifies the sound of draining water.
Original utility sink ("tray" threw me too) was a huge double sink made out of concrete. I have no idea how my parents got it in the basement. When the skinny little iron legs rusted and bent, cracking the sink and breaking the drainpipe, it took a sledgehammer to break it into portable chunks. Current utility sink is a cheap plastic thing. Someday when I finish the laundry room, I'm gong to see if a professional plumbing supply has something less flimsy.