I've developed a crude workaround for the annoying bug that adds a million <span> tags to the content editor for misspelled words.
1) Save the affected HTML in the <body> of an HTML file. 2) Add this script to the header. 3) Load the HTML file in your browser. 4) Copy the resulting HTML back into Blackboard.
EDIT #2: I've updated the hack to fix a few cases where not all the <span> tags would be removed.