When you're painting with very fluid paint, it's may happen that you accidentally splatter some where you hadn't intended. If you notice it while the splatters are still wet, you can wipe them off or brush them in. If you notice only when the splatters are dry, you can either paint over them, or ignore them as part of what gives the painting character.
Whether it's really a problem of not depends on the color splattered, and what style the painting is in. If it's a photorealistic painting, then it'll likely look like a mistake; if it's an expressionist-style painting, then it'll likely look like part of the painting.
Whether it's really a problem of not depends on the color splattered, and what style the painting is in. If it's a photorealistic painting, then it'll likely look like a mistake; if it's an expressionist-style painting, then it'll likely look like part of the painting.