How does one know a great book with out consuming some junk? We learn when we do it wrong up much more often than when do it right. It is not always clear in the beginning that putting business logic in with the view or the data layer code will later be impossibly difficult to untangle. I would suggest read what you want then do what you think is best. It doesn't matter if it is completely correct. (whatever correct is) Some good peer review will keep the bad trouble away, or at least the decision to keep it will be made with the eyes open. Nothing will create a great programmer faster than untangling those darn tangles.