When playing WM there seems to be strong positive feedback loops. Each girl added makes money at a decent clip and gangs become profitable very fast. Negative feedback seems limited and fairly inconsequential.
There are the three usual ways to deal with this:
-Reduce positive loops: Currently many choices have exceptional ROI. Catacombs and whoring seem to top the lists. Ways to contain this for example having a girls level cap the price per trick; no mater how awesome her stats/traits it takes a while for her to reach her full potential. Reducing catacomb profit or having prerequisites to get the better loot appears to be the most popular for reducing the catacomb job.
ROI is a bit of an understatement as it stands now. There is very little investment. (You can never buy a slave and end up with a ton of girls in your brothel) and a metric ass ton of return. It's a bit unbalanced.
-Money sinks: Currently getting new building and buying gang weapons/items/slaves are the money sinks. In my experience all can pretty much be ignored. With the exception of buildings all of them seem a bit on the light side. On a side note it makes an interesting challenge if you never buy a slave.
Tried the not buying slave thing, also tried ramping up the cost of the money sinks in the config file. Even got it to the point where I had to have the 2 "starter" gangs getting at least 2 pieces of territory a week and get 4 girls able to whore day and night for at least 2 months before they needed rest or I would not be able to turn a profit to do anything else and would eventually negative out. (Conversly this was the hardest I could get the game without making the early game unplayable.)
However, between breaking "walk around" girls in the dungeon and the freebies you get from customers that can't pay. You eventually can put all your girls on training in the morning whoring in the evening. Your income then reaches a point of critical mass and you start earning money hand over fist. If you put some girls on catacombs or have your gangs start sabotaging rivals, you earn even more income with little consequence.
So I guess this is a long winded way of saying Money sinks just won't work.
-Negative feedback: There are a few of these already in existence; maintenance, filth, beasts, matron, bribery and consumables. The problem with escalating them is they very become irritating rather than fun. eg the maid got sick and filth shuts down the business. The least irritating ones are either fun (no ideas here) or silent such as better girls require more funds in maintenance. One idea it is to tweak the customer count equation so that it becomes less profitable per incremental whore. Personal experience shows ambient visitors are sufficient to produce sufficient tricks per whore such that rarely do any go wanting.
Note also that you can get those ambients without ever spending a dime in advertising. or giving a crap if they are happy for that matter.
Bringing cash-flow into closer balance makes money more challenging/interesting for the business players. However making them too close risk alienating the girl collectors.
And this is the real heart of it, how to make the game challenging to the power players while still making it appealing to casuals. Solution, the config file. A this point in time the game is pretty easy. So this is newbie mode right here.
Any new alterations to the games balance should have a corresponding option in the config file to tweek it down. (Dev's are already doing this, Case in point, when Dagoth altered how recruiting gangs work.)