With the right paint.
But the bumpers on cars are not 30+ years old plastic thats weathered and dried out.
My thinking was more along the lines of plastic fuel tanks and motor bike plastics. Fuel tanks are a different issue, but motorbike side plastics are not that different.
Twin catchers are hard to find.
If you have a good orange one, painting over it is basically throwing away a good orange catcher that might have been worth a lot of money to someone or might have been a swap for a good green one. (i doubt it the orange ones are by far more common)
Im sure its a ways off yet, if i remember right you have a big pile of mowers to restore.