First of all, sanforized denim/cotton still shrinks (as I said, up to 4%, mostly in length), just not much compared to unsanforized.
And Sigmatic, I agree with you about wanting to have more knowledgeable staff. Who wouldn't want that? The point I am just trying to convey is that there is general knowledge about the product, and then there is more technical stuff. How many car salesmen can explain to you about how all the inner workings of an automobile are made and assembled? The same thing with denim. How many sales associates can explain to you the construction of the denim, the weave, etc. unless they are specifically trained to do so?
If you walk into a denim store, I am sure as hell those SAs are knowledgeable about denim. If you walk into a boutique, it will be unlikely that the SA has the same knowledge unless they just happen to be a denim-head. I think this rule applies to any store.