Nashy, I see your point as you do not want to burn bridges. However, it seems obvious to me that they are exploiting the situation because they can get away with it. Of course you want to maintain good relations with them, but at the same time, you are entitled to fair treatment. The situation with not being on the ground observing exactly what is going on, works against you and for them. I reckon it is entirely doable in getting to a situation where they realise you know better, expect better but without being nasty or burning bridges. The only way realy is being there at least once or twice, so they come to realise that you know exactly what is involved and then unable to be exploited.
You have to give them no wriggle room - that means, making sure the vehicle is as clean as possible before shipping and HAVING proof that this is so - ie photos. Being there when they offload so they know you know that is clean and animals did not shit all over it during the voyage (or whatever ridiculous excuse they might cook up). And let them know that this is what you are doing - in other words forget about ambushing them or trying to catch them out. Just make sure they know that it will be impossible for them to bullshit. This is why I suggest striking up a conversation with the AQIS officer before things happen - so he knows that you have ensured it is clean, you have the proof (photos + inspection certificate) and you will be there to witness offloading and first inspection. As you go through the inspection with the AQIS guy, there is simply no room to manouver. It might be that the officer could try to be difficult, but I actually doubt it. In any case, ask them for thier current Work Instruction so they know that you know what needs doing and how inspections are meant to go. If they refuse, let me know, I have a copy of the work instruction that I obtained from DAFF when I fought my battle. That is where the photos of QRM I posted comes from. I did want to post the whole work instruction without thier permission. At the end of the day, they should come to know you as someone who is straight, doing the right things and not be BS'd - respect both ways.