This is what the previous owners left us in the bathroom.
I think these knobs used to be shiny brass, but that must have been a long time ago. Judging by the decor in the rest of the bathroom - tons of shiny gold-look brass - the bathroom was re-done in the 1990s and the knobs are probably 15-20 years old.
I looked into restoring them with scrubs and polishes, but they weren't solid brass. With brass-plating, once they're this far gone, there's not much to be done. I considered buying a metallic spray paint and making a mess in the backyard trying to get paint onto every edge of the knobs, but they'd need to be sanded down first to even out the tarnished surfaces, and it felt like more work than I was willing to put in for a bunch of knobs. Not to mention that my husband was not delighted with the idea of me screwing around with spray paint in the backyard, even though I reassured him the grass would only look shiny for a week or two while it grew out.
A short trip to Home Depot, fifteen minutes with a screwdriver, and I've got a bathroom that looks a tiny bit less neglected and dated.
The white plastic knobs are a little bigger than the old ones, but not awkwardly so. Most importantly, humidity won't bother them in the least, and they'll be easy to clean.
There's nothing I can do about the shiny gold trim on the shower doors, so I'll have to live with a little bit of bathroom bling. But I'm glad I was able to upgrade the cabinets to a smooth white-on-white look. Baby steps, right? Maybe new sink faucets next!