1. Comments are there to tell WHY the code is doing what it is doing, not necessarily what the code is doing. I deal with code all the time that has comments that tell me what I can easily learn by reading the code, but they don't tell me why so when it is broken I don't know if it is because there is a subtle problem with the code or that the developer didn't know what they were doing.
2. After literally getting headaches from reading code written by other people I came up with a simple metric: The complexity of the coding solution to a problem is inversely proportional to how well the developer understood the problem they were trying to solve. In other words, someone who understands the problem will have a simpler solution than someone who doesn't understand the problem as well. You can apply this metric to things other than code, too, but it is usually very apparent with software.