Can you paint porcelain sinks Or how can you get stains out sink that won't come out with bleach?

Porcelain is actually glass. Iron castings in the shape of your sink are covered with powdered glass then "fired" to melt the glass to the iron. I don't know of many paints that can stick to glass, so painting a porcelain sink is almost impossible. That is, conventional painting... you can, however, contract with companies that use a powdered paint or other processes to coat a bathtub. I don't think the process has held up well on kitchen sinks. If the sinks are stained brown from rust, the stain could be coming up from a crack in the porcelain. That's difficult to remove, but you could try CLR or some other calcium and lime remover. Some of them work on brown rust stains as well. Sometimes it just gets to the point where it's not worth the trouble and you just have to give up and buy a new sink.