North High School, Montbello High School and East High School (probably in that order) all have bad reputations. However, as a former Denver Public Schools teacher, I have noticed that many schools get a bad reputation, even when they don't deserve it. Just because a school isn't in a great part of town doesn't mean the students aren't willing to learn or desiring a good eduction. In fact, oftentimes, the opposite is true. They may have the desire to change the path from what their parents have been on and strive to do more and become more.
I also know of students who have opted to leave what many would consider better schools to attend some of these poorly viewed schools for various reasons. It all depends on the perspective I guess. Some are academically behind but that isn't the picture of the entire student body.
Now, having said that, I wouldn't go out of my way to move into any of these neighborhoods, but I also enjoy living outside of the city.