Whilst I don't actually know the answer for this but
For YAVE, only explicit in departing VFR traffic required to squawk 1000 (at the holding point). I presume YAVE arrivals also squawk 1000 at 50NM?
This may be the way of telling the difference; ie for YMAV squawk 1000; easy to pick up; vs YAVE still on 1200; and leaving, well you're headed away; when on radar.
Re calling for an advisory: The problem with calling for an advisory is the answer you'll be given; i.e. is it practical in anyway. "There are multiple bogeys every faarken where, look out; behind, in front, crossing, same direction, opposite direction, descending, climbing etc." Was that any help? So why ask?
I heard once, walking by radar:
open mic "multiple traffic observed, 517 paints, no wait it's closer to 313, good luck"
close mic FAAAARKEN IDIOT, calling for traffic there!