Every teacher needs to defend about 15 to 20 undergraduate thesis and 10 master thesis every year. Every year, master's and doctoral dissertations from other schools will be sent for blind evaluation, and about 3 papers will be submitted. Such a big number should be read and commented in 10 days. Teachers and other things such as teaching and administration are not allowed to look too carefully. It takes more than 30 minutes to finish the master's thesis and 20 minutes to finish the undergraduate thesis.
However, since we are teachers, marking papers is also skillful. Be sure to read the abstract, table of contents, conclusion, postscript and literature carefully, mainly to see whether the main contents such as research significance, research hypothesis, model, method and data source are up to standard, whether the logic is self-consistent, whether the literature is thoroughly understood, whether the latest mainstream research results are cited and so on. Basically, you can get a general understanding in 10 minutes. If you have questions or are interested, go to the details and prepare three questions and suggestions.
As for how to judge whether the paper has passed or not, except the level is passable, just look at the postscript or thank you. If you are an on-the-job graduate student, or a master's doctor who has not graduated near the academic system, you will generally be lenient and let go between passing and failing.