I changed permissions in three WP sites to 766 in the wp-content directory so the media upload feature could be used. However, this kills the template stylesheet somehow and the content is displayed unstyled. I reset it and the contents back to 755 and everything worked again. I didn't try 777.
I assume this is a bug of some kind. Is there a workaround so I can have some security in that directory and have styles applied too?