Yes because they're all flood damaged... You've been warned.
Technically, any vehicle that was flood-damaged was put on the (surprisingly named) flood damaged vehicles register. You then had a maximum of (I think??) 60 days to have the car professionally repaired and then inspected by QLD Transport. They went over the car themselves, as well as going through your receipts showing the work that had been done. If they were happy, they removed the vehicle from the register, if not, or if your time limit expired, then your car is still able to be driven/registered/sold, but you can't get the VIN off the register (no matter what work you do in future).
So, if you're concerned about a car having been flood-damaged and not repaired, then a quick call to QLD Transport with the details should give you an answer. What you won't be able to tell is whether the car was damaged and then repaired, but I know the inspectors were casting a *very* close eye over the cars that they inspected, so I'd be happy that they had been repaired to a high standard. I know this won't be sufficient for some people, but for most of us who will then drive our 4WDs straight through the nearest mud-hole, I don't think there's really much cause for concern.
A plan ticket from Sydney to Bris isn't much, and it's only a day's drive back - I'd have no hesitation in buying interstate. Obviously I'll always suggest getting an RACQ report done on any vehicle you're interested in, but past that, I think it's quite do-able. We bought our Pathfinder from the Gold Coast, which is about twice as far away. I'd arranged the dealer to take the car to RACQ for the inspection, and I had friends go down there to have a look at it and see if the photos were accurate (it was in even better condition than the photos let on). So we transferred the money to the dealer, and the first time I laid eyes on the car was when I arrived at my Dad's place, fresh off a plane. Granted, you've got cross-state rego to deal with as well, but that's not a huge issue, especially if you're not buying a highly-modified vehicle.
Good luck with whatever you decide!
Matto