So my problem is I have solved many of the quest in the town but I can't get nenny to talk about the thief again. It's just.. stuck. I can't get the scent, I can't get the veil. Is there some kind of command line code I can use to trigger the event of knowing that Luis is the thief? or simply 'spawning' the items I need or make Luis die?

You can use a editor to create the items in your inventory.
http://bootstrike.com/Torment/hints.php
Ctrl+F -> Search for -> Infinity Engine Savegame Editor by Guillaume

Thanks!
wouldn't this corrupt my save game(s) after that point? I've read that some people had issues with that.
But as I've progressed yesterday, I came to the conclusion that I don't need the brothel parts at all, all optional. But might there be some point where you could cause the quest to become broken, to be never solved because the dialogue option is gone missing?

I had no problems with this editor (I've used this to spawn items in two different playthroughs). But if you're worried, make a backup of your save folder. I don't know, sorry.
Have you installed Qwinn's fixpack? It fixes lots of bugs.

among other things as unfinished business, I have.

Have you managed to solve the problem?

you know, I thought mine was broken for the longest time. No matter what I tried I could NOT get this to progress. I came back a couple levels later (and with a few more points in INT I believe) and a new dialogue option appeared with one of the characters...did a couple more smaller quests for the individual character then the rest of the story went the way it was supposed to

*SPOILERS possibly*


went and talked to the wardrobe and was able to wrestle the veil from his...err...drawers...



So no, I don't think waiting will hurt anything.

No, not so far, I'm about to leave the pillar of skulls. might update this when I return to the city. okay, good to hear that there is a possibility that this isn't broken. although my INT states are high. I suppose. I'm not certain right now.

Normally this isn't something I do, or recommend for a game like planescape - but have you checked a FAQ? Sometimes one teeeeensy little seemingly unrelated character/quest/item is the key to the whole thing. If your int is high, that's what I'd do next.

Some quests have multiple solutions but they may not be available if you don't have a high score in the required stat.
This walkthrough is very extensive and lists all the attribute requirements for the various dialogue options and quest resolutions. Needless to say it contains massive spoilers
http://www.gamefaqs.com/pc/187975-planescape-torment/faqs/7964