Where did you see painted toilets? I have never seen one, but you could ask next time you see one. I have a gray toilet but it is not painted. Color was incorporated into it at the time of manufacture. I have also had a red and a black toilet in my long lifetime.

I once painted a sink with a product called Tough as Tile. The box said it was for bathroom fixtures and appliances that don't radiate heat.

It has a strong odor that gave me a headache, but it held up well. You may want to try it on something else first to see if you like the results.

I used "Tough as Tile" spray version to paint shower tiles a different color and it worked great but I was doing the entire surface. Don't think a spray can is what you need to paint stipes. I bought it Home Depot

It also comes in a non spray version which I used on a tub. The end result was nice - but it was very difficult to use. The product was very thick. And although the directions said to apply thin coats, I don't see how that was possible. I used a plastic squueggee to spread the paint after the initial briushing.