It was a small, expensive-looking, landscape painting in beautiful colors.
The second comma should be removed. This is because "landscape" is not a separable adjective (not an adjective at all, in fact). That is, while we can say that the painting is small, and also that the painting is expensive-looking, we cannot say that the painting is landscape.
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The second comma should be removed. This is because "landscape" is not a separable adjective (not an adjective at all, in fact). That is, while we can say that the painting is small, and also that the painting is expensive-looking, we cannot say that the painting is landscape.