Earlier quoted context omitted.
Exactly, being rude and blunt right away is probably about the most efficient thing they can do. I bet 70% of the time people change their stories when confronted with that line.
I couldn't disagree more. The police are there to gather evidence. They're effectively tainting evidence if they mistreat people or ask leading questions or the like. You'd better believe it matters when they come after you for (say) making false statements to the police, and it's their word against yours, and the court always sides with the cops.
I don't understand your point at all about "tainting evidence" and how that could possibly follow from brusque questioning.