Perhaps collecting some sort of 'Duokan:known bugs' ?
Anyway, some characters mess up some pages - and those would be nice to get recorded as well.
Apostrophes seem to take up a whole character width and does not look so good. Noticed in Epub and Mobi. Something had me think it could also relate a bit to the text-2-speech functions, i.e. perhaps there are a bit more involved then merely the looks of the character ?
http://en.wikipedia.org/wiki/Apostrophe