IMO, if they do not sit together side by side, the difference is really not that pronounced. Even my Panasonic microwave w/ trim kit sits just above the Miele oven, I can see minor color/quality differences. It does not bother me at all, as I knew these differences are expected. I would not pay thousands more to get rid of the differences. :-)

You don't. Just don't focus on slight differences and it'll be fine. I have four different kinds on my cooking appliances, plus two different on faucets, and they all blend find. What doesn't is my airgap, which has a decidedly yellow tinge, whereas the faucet is uninflected gray. One is in the center and the other is on the side, so about a foot apart. No one notices it.

That said, if you want to be sure, get a gray photo balance card, or even better, a black/white/gray set. It should be less than $10 for a set at your local photography store or on Amazon. First assess the store lighting by seeing what color the white card (or a regular white piece of paper) is. See if it looks more yellow, blue, green or red than normal. Next, hold the gray card against the steel and write down whether the steel is darker or lighter. Then look to see if it's more yellow, blue, green or red than the card, and write down what color and how much (a little, a lot, etc.) This can be cancelled out by the lighting, however, but I'm not going to write pages of how to figure that out. You can do it by intuition nearly as well as if you were using a color meter. If you think that the lighting color is affecting what you see, try to go to a different store, or even see if they can show you the piece in the sunlight. It doesn't matter so much if you're choosing all your pieces from the same store with the same lighting. You can then compare your notes to see which ones have different undertones and which ones are farthest from neutral gray.

Or just go with my first answer, and figure that unlike putting aluminum and stainless in the same room (aluminum runs very blue), stainless pretty well matches and you'll get as many variations from shadows as from the different minerals.

Appliances manufacturers source their stainless steel from different factories, or even same factories but from different runs, so that even appliances within the same brand can actually have different-looking SS. As others have said, don't worry about it. Even if you pick appliances in the store that look like they have the same SS, the actual appliances delivered to your house may be from SS from different factories/different runs, and will not look exactly the same. Don't worry about it or you will make yourself crazy. Move on to other things to worry about with your appliances.

I have Bosch range and dishwasher, Kobe hood, Samsung fridge and Monogram microwave. Oh, and Breville toaster oven. They all work fine together except the dishwasher. It's distinctly more of a whitish silver, and clashes most with the range. Go figure. Not sure if it's because they're different series or more due to what AK says. I don't know if smarter shopping would have helped, but do have to say, going on two years later it still bothers me. Even in unbrushed stainless, the Petsmart dog dishes match the rest better, color-wise.

I have a Kitchen Aid dishwasher, Panasonic microwave, GE range and LG fridge. They all look great and I can't see big differences in the finish. Most don't smudge much in our home either. The KA dishwasher is the worse, but also likely the one to get smudged the most. We chose ours based on features, reviews and overall best function for our needs.