Sadly, the ability to affect your ambient wealth is too great when you factor in friends and so on. While I'd like to base the ambient profits on real sales, it's easier and -safer- if the GMs do their job and determine what the ambient profits should be.
Bars that automatically take a cut of profits will not take a cut of these profits, just the -real- profits that come from actual usage of the bar.
Does this mean it's possible for someone to run a store with nothing for sale and still make money? Yes ... until I catch your cheating ass and beat the chyen out of your corpse a few times over.
This way, if you 'work' the system, your cheating, not just being clever.
Don't rely on us knowing you shouldn't be making X chyen, be honest and tell us.