Ok, so you are in a wormhole for either legitimate or nefarious purposes. Now what is the first thing you do when you enter a wormhole? Bookmark the entrance. Second thing? Dscan. Any force fields? If yes, your not selling this wormhole today.
Your initial dscan is not enough to show you have an unoccupied
system. Larger systems will have some planets outside your range.
While you probably can scan down towers with combat probes, the far
simpler way is to warp to the vicinity of every planet until you (a)
have the planet on dscan, and (b) confirmed you can not see a force
Anything else you see is potential loot. A
hanger of any kind with an inactive field is an invitation to bring some
friends and play loot pinata. Even someone with as little 'active' pvp
as me would play with such a present.
I would not recommend that you spend time simply looking for wormholes to sell. Finding, then selling wormholes takes time. I am yet to find someone who enjoys scanning for it's own sake. Certainly not me.
That said, there are times you will be scanning anyway. Whether it is looking for a way to empire space for POS fuel or to sell goodies. Whether it is because you have an overfond liking for wormhole explosions (bad pirates, bad bad pirates - now go sit in the corner. Or catch me and then blow me up. Whatever works).
In this market, what most players want to buy is an entrance to an unoccupied wormhole system. Your potential buyers are after a particular type of system, but that is a topic for a later post.
The majority of wormhole buyers are purchasing an entrance to an wormhole system that has no active towers.
Next: What are buyers looking for?