Re: Namaz and Nailpolish
The reason is simple which has been ingrained in our minds from the childhood with the help of ahadees on these kind of subjects.
We are not supposed to question the Ahadees, just take them as they are from books of sahih ahadees. As the argument goes people spent their lives examining and collecting these ahadees therefore there is no doubt in their authenticity. You will soon see some one quoting ahadees on the subject from some book of Sahih Ahadees.