Grading student behavior or effort is a tricky and an inappropriate practice. To grade things such as work ethic, effort, participation or behavior, when these things are not part of a curriculum, and usually not explicitly taught, is inappropriate. Teachers often do not present clear criteria for meeting expectations in these areas, which makes grading them very subjective.
Mike is new to blogging, and has some great ideas. This quote is a small part of a larger blog post, which is well thought out and worth the read. He nails it here by stating that work ethic is not explicitly taught. I'd take it one step further and state that work ethic is something that many of us punish kids for when they don't have the skills. We not only don't teach it, we hide what it is until we catch a kid not "trying hard enough", as if we can gauge that to begin with.