Stefan
Thank you for that little GEM of information. I've been plagued by the problem of trying to back out a font setting from a Character style and you have just provided the key which cracks this problem.
When a Character style has had any typeface applied to it, you can't 'remove' that font attribute from the Character style ever again. You can reassign it to a different typeface but you can't clear the font, either in the Modify Style dialog, nor with VBA.
The only way I found I could do it was by 'deleting' the character style (which clears all its settings). In the case of built-in character styles, deleting the style doesn't really remove the style but it does hide the style AND clear all its customised settings. I say customised settings because Word appears to have some character attributes by default (Strong is bold, Emphasis is Italic etc)
Now you come in like some white knight and give me the clue that all this fiddling around to remove the typeface could have been solved by a simple
Update style to match selection. AMAZING...