Personally, I hate painted hinges. I removed all of mine and polished the solid brass and or replaced them as needed.

If they are not brass(even if they are) yes they can be painted, they just shouldn't be, IMO

If those are real solid brass, I'll take them!!! Seriously if they are real then just get a buffer or grinder, put on a buffing wheel, spray clear lacquer (dries fast) your done. You might need a wire wheel also to get the paint off, then buff. You could probably do a set in 10 minutes. Solid brass hinges are pretty expensive, I wouldn't replace with cheap garbage if they are real.

Painting them... you can see they don't look much better. If there not solid brass just get new ones.

I don't think those are the original hinges.

I took off 60 hinges of my cabinet doors, and replaced them. Mine were the old dark brass, and were disgustingly dirty and the color no longer matched my new cabinet color. I considered painting them, and would have if it had only been a few of them. If fact I did paint the hinges on one door as there was not a matching nickel finish hinge available for that one. But that's for cabinets. For doors, especially light painted doors, I prefer the hinges to match. I painted mine (they were already painted the previous color) and I think it is a big improvement.

Kinda silly to invest time and money into equipment to clean hinges that you have no interest in using.

I used to throw old hinges into a metal paint can and submerge them in lacquer thinner with a cover on the can. I few hours later, the paint residue just washes off.

The Crock Pot system works well for latex paint, but years of oil paint require a strong solvent or paint stripper.

Those are pre-war hinges and you might have to go to a specialty hardware store to find exact replacements. If the old hinges clean up well, you might be able to polish them, even if they are not solid brass. Don't use anything abrasive on them. Old fashioned "Brasso" brass polish could be just the ticket.. If you get them nice and bright and want to keep them that way, spray them with a light coat of lacquer thinner.

Here is a site where I got new oneshttp://www.houseofantiquehardware.com/brushed-nickel-hinges-butt-ball-finial-3-1-2?sc=10&category=160

You have already put satin nickel hardware on the doors.......remove the doors and order satin nickel hinges that go with the knobs and replace the brass install the satin nickel.