Its one thing protecting your borders and stopping illegal contrabands from entering the country, but its another thing being rude and insulting to VISITORS of your country.
Can't they do their job but at the same time be courteous and inviting befitting a developed nation? Be as aggressive as you want AFTER you've found ILLEGAL items, stop bloody treating everyone like they're criminals from the get go.
Australian Customs are doing their country a disservice if they continue to act like this.