Set Paid Device (Under BlueTooth) to "Set as Authorised" and files will automatically be accepted.
As we always say here on AAS "Read The Manual".
I did RTFM before I asked the question, but I see the question may be slightly mis-interpreted. The idea is that any device can connect and deliver a picture/contact/etc to the phone without having to be paired or authorised. Does that make the question more obvious?
It would be a nice way to fill someonebody's phone memory, if you want to cause trouble.
That's why the prompts are there (to prevent such things to happen; deliberately or by accident).
But that's exactly the problem - for our client we want to have a drop-box via bluetooth for visitors to drop pictures on a memory card that the client can later review, and use any of them for promo material. But it looks like we're going to have to get some specialist bluetooth equipment for this, I just reckoned it would be possible for someone to have written some software that runs on the phone and intercepts bluetooth connections but doesn't explicitly prompt for acceptance. So if anyone knows of anything like this... I'd like to know.