We all know Walt answers questions. Heck, I answer any question someone asks me in real life. The thing is, some questions are best left unasked. There are points when curiosity becomes rude.
Nobody has caught Walt telling a lie or being unprofessional. His word that it is pharma grade should be good enough. A businessman is allowed to have some secrets about how he makes his product. I've seen too many people asking "honest" questions (in other places) turn around and attempt to use the knowledge for profit. Like I said, there is a point when curiosity becomes rude and impolite.