- The kid was having a bad day.
- It's a bad test.
- The kid is bad at taking tests.
As for the second, I'm willing to believe it far more for a teacher made test than a large-scale version. Why? Most teachers have had no formal training in assessment. I've seen plenty of poorly developed items and poorly constructed tests at the classroom level---including my own. For a lot of my classroom career, I would not have been able to tell you whether or not an item was good---Did it measure what I wanted it to measure? Was it free from bias? Was the content accurate? Did the analysis of the student responses support the goal of the whole assessment? Bad tests exist. But they are not the ones your state is using to measure student learning. Don't like the way the results are used? That's a whole different discussion.
The last reason is similar to the first in that it does exist...but very rarely. In my classroom career, I only ran across one student who was truly terrible with tests. She was in an AP class and could answer nearly any question I asked her in a conversation. On paper---even with the benefit of her textbook and all of her notes, labs, and assignments---she couldn't pick the right answer. She is the only student I ever discouraged from taking the AP test. I tried coaching her all year...we went over questions and talked about the thinking involved with answering them...but we just couldn't get her enough strategies to make it work. So, she was one out of thousands that I could truly say number 3 fit. As for the rest, I rarely made a concerted effort at "test prep." I did work with students on metacognition---being aware of how they were making choices with questions. But the most important thing to do was focus on content and teach to the standards.
Lots of people---both in and out of the classroom---don't like large-scale testing. I'm not one of them, as unpopular as it might be to say so. But then, I've had the benefit of being involved with writing items, test builds, scoring sessions, rangefinding, and more. I've seen the entire sausage get made. However, I don't like how the scores from these tests get used---for graduation requirements, student placement, teacher evaluation, and other uses for which the tests were never intended. But we can't disconnect those from testing by attacking the tests themselves with arguments about them being bad.