Well, it's true that a little plagiarism is good because it shows that you included ideas and arguments by other writers or credible sources. Having a 0 score may indicate a lack of resourced content since a little plagiarism shows that you researched well. However, it should be noted that what is liked is a little plagiarism but not a lot. Anything less than 5-10% is good if well referenced and cited using the right referencing formats like APA, MLA, and Chicago among others. A little is good but not too much.