Captaindejavu, from the definitions section of the act:
""goods" means movable
personal property of any kind and, without limiting the generality of the expression, includes
documents, vessels and
aircraft. "
Goods subject the the control of the Customs are defined in section 30, which is long, dry and cumbersome.
Suffice to say, my understanding and experience is that Customs can search anything that is imported or due for export, no ifs, buts, explanations or warrants required. Given the number of lawyers that get knocked over, I imagine any loopholes would have been found and exploited by now.
Section 186A is long, with a number of caveats, which is why I didn't post it. It sets the parameters for the power to copy documents. The Officer must be satisfied that the doocuments MAY contain info related to an offence committed against a number of acts, including the import / export of Prohibited Goods, an offence against a prescribed Act and s17 of the ASIO Act. Basically, they're not allowed a free-for-all copying spree with your stuff. However, these conditions are not hard to satisfy.
Searching people requires some justification (s219) and dip bags are out, but anything else is free game.
In some ways the Customs powers are much wider than those of the police.
Roamingwolf is right in that Customs are not interested in general X rated porn (ie adults doing non-violent stuff to each other), your secret second family in Thailand or hate mail to John Howard. They are concentrating on kiddie porn, violent porn (and some of the stuff out there is simply vile), drug / weapon smuggling and the dreaded CT.
I can't imagine many of you guys would be carrying that sort of stuff around with you, and if you are, you probably deserve what you get.
Unfortunately, if a couple of pilots have been found with nasty stuff, you may all come in for a bit of a targetting for a while. This is the way LEAs operate.