Admitting evil

I don't understand why people decide to admit that they cut corners to those who are grading them. As if the honesty will get them a better grade? If you manage to find the information needed to summarize a play online, without cracking a book, you do NOT write that you used internet summaries on your paper. You simply defend to the end that you read it, but it was long and you don't retain well. That ties up the loose ends and won't get you caught for academic misconduct, Mr. G.
Now, when you reach the classroom, you do not participate in the conversation, and you do not try and counter what others are saying (others who have read the book). That is a simple idea: sit down and keep your mouth shut. If you are asked for input, then you cite a very specific detail that is so trivial that it could be interpreted in infinite number of ways.