when i see someone on the long range scanners (4-14k away) my Harvester beings with:
"This unit requests Subject <name> unit to cut engines. Ready for scan."
Then i wont go further until i do
":::Scanning:::"
Then, and only then do i differ friend from foe (there have been a few exceptions, only few)
Then it depends on the characters willingness to RP. If they put up a good show i say:
"Subject unit does not posses harvestable resources"
"Subject <name> may proceed."
If he is a real dirtbag, PVPwhore or simply on Harvester KoS list i follow it with
"Harvestable units found: Subject <name>."
":::Commencing Harvest Protocol:::"
This is unfortunately what it often comes down too. I like letting Traders go without paying
credit resources IF they are willing to spend a minute-or-two chatting.