Whilst this should probably be split into it's own thread,
So customs does a bag search, so what? They already pick out people at random for searches, (spending a day overlooking the AQIS / customs line was certainly very enlightening). Pretty much if you want to cross the border and / or take stuff with you across the border you've all but agreed to have any bags searched on re-entry to Australia. Most of the time (despite what you see on "border security"), they find nothing, and then simply welcome the person into the country. Unless my day there was on a quiet day, most travelers who don't already have a bee in their bonnet seemed to take the search as part and parcel of international travel (although I was assured by the AQIS officers that it was a pretty standard day).
I've had bags x-ray'd and searched in the past (ticking yes on one of those questions all but guarantees it), it was no big deal. So I do know what a search is like.
As I already said, customs take each piece of information they receive and then make a judgement call. As far as I know there is no onus on them preforming a search just because they where told about a person (since that in itself could be used as a distraction technique if I did want to sneak something across, make up a few porkies about other pax reducing the likelihood of me getting pulled up).