Judging by my sales at Smashwords, and judging by the test I did (covered in the OP), I standby my opinion that most readers open the Smashwords book on their Nook, Kindle, etc and you know, read it. Shocking I know! These readers do not have any problems, which is evident by their continued purchase of more books from Smashwords.
It is only a select few that will ever look at the code, and of them a small precent of them will care that the code is not as clean as they would like. That tiny group will never be happy.