In my latest paper for a communications class (the one I asked the "Black or African American" question over) I found basic errors, like the ones you cited, made by my classmates when they were talking of increases and decreases of things. In a way, I'm glad I wrote a less research-intensive portion of the paper, since it allowed me to spend the time finding their errors and fixing them.
On a much more funny note, this picture amused me. Wish I'd seen it for Easter.
