What about the people who would become the soul shriven? Surely the soul cairn is a paradise considered to coldharbour? Soul trapping Lolgrolf would be a kindness, surely?

I'm not sure exactly what my character's morality is (he did Missing In Action to help the Greymanes, but he broke into Ogmund's house for Ondolemar(sp?) for the thrill of thievery), but I figure he'd only trap evil people, to condemn them to the Soul Cairn.

I hear you here, but then you become a vigilante of souls almost. It may (or may not, can't remember) have been pointed out earlier in the thread that vigilante justice is sort of iffy. What gives anyone the authority to make those sorts of decisions? And that's sorta the gray area, right? Because presumably you wouldn't just go around soul trapping citizens of Whiterun or Solitude for the sake of having a steady supply of black souls. So are all hostiles evil? Bandits? Vampires? Are they all evil?  Serious question! I'm interested to know your thoughts.  

I'll tell you the smart enterpriser that kicks off that industry would have more power than any king or emperor etc. Crypt crawlers could hire their services out to smash through armies of the draugr for extra profit, certified evil souls only! Mercenaries could scour the lands for certified bandits and gain bonuses from local lords for refilled soul gems certified made by evil bandits! And hunters, go after that big game harvest, not only do you gain meat, hides and bones, but now soul gem fills as well which could be a major profit boon..... Oooohhh the possibilities!

I really like the way you've thought this through.  I feel like I see at least an awesome RP Profile, Blog, (possibly even a build!) stemming from this idea. Speech, Enchanting, Conjuration, pick your weapon of choice... Mhm. Could totally see that shit. 

Hm... A fair point. If the alternative is Coldharbour then maybe wasting away in the Soul Cairn doesn't seem quite as awful a fate. Could be some cool RP from that angle too if you were playing through as a vampire. 

I guess people like Grelod, any Thalmor…vampires are iffy, though, because feeding isn't something they do For The Evulz.

This sounds rather like a guy who thinks he has right to decide who deserves to live and who doesn't, and bases these decisions solely on who he personally likes. He has no doubt he can kill people like Grelod while she is technically an innocent civillian (unless I've missed the moment when being a bitch became a crime) or the Thalmor who actually are guys who do their job, while deciding that vampires are poor harmless pansies, obviously because he hadn't had his family slaughtered by them.

This is not a guy I'd call even neutral, much less good. But that's just me.

I didn't use soul trap. I depended solely on store bought or found soul gems. I would also never even allow myself to keep a black soul gem in my inventory. It certainly made gameplay more challenging as the knight cleric, as absorb magicka drains a lot of soul energy per hit. So I had to be conservative and only charge my weapon when fighting mages.