If asterisks were used solely for radio communications, would you personally find it confusing? Would an agent/editor/publisher reject it outright?
Thanks.
Yes it does depend on context, although my guess though is that you'd really be tagging them just like quotation marks, so why not just use quotation marks?
But possibly it would work fine. I haven't seen it in practice so really I don't know
However, thinking worst case scenario (and I should make it clear I've never been on the publishing side of this business at all*, so purely a opinion):
A stressed manuscript reader, working their way through the endless in-pile of submissions, might pick up yours flick through it and find pages of asterisks, quickly say Woa! Incorrect/Non-standard punctuation, then think: 'this suggests that this writer either has other weird issues all the way through the manuscript or perhaps doesn't understand punctuation. Probable massive hassle.' And instantly without even a cursory look at your content (which may be perfect otherwise, including your radio com dialogue), your manuscript gets sent to the reject pile.
I have no idea how likely such a worst case as described might be. Do you want to take the risk?
But if you are only ever going to self publish then hey, what the hell!
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* The closest experience I've had of this is having to choose candidates from a pile of a good couple of thousand CV's - and believe me when faced with such a mountain of information and only so many hours in the day, in the first cut you automatically cull for the smallest of reasons: weird paper, spotting an obvious spelling mistakes, if it is a junior position for graduates and no experience is required then only pick those with firsts or two-ones (and if that still produces a huge pile, then just throw out the two-ones...) etc...