This is what the free market is all about. If people are going to spend $0.99 on a fart app, then people should be producing fart apps. Does it reflect poorly on today's society, maybe, maybe not. How much can you get for a buck these days? Not much. Why not have something sophomoric? Do we really need to be THAT serious ALL the time?
I have been doing software development for almost 10 years now and have worked on some small, several thousand dollar projects and some large, several million dollar projects. If you can pump out some code that farts and make 30K in 8 days, do it. That is a pretty good ROI. Do 3 of those a year and you are making 90k, not a bad salary.
You are absolutely correct when describing the free market, with the presumption however, that some consumers are dumbasses and will buy anything.
I am personally still waiting for more useful applications from the app store, a video recorder being one of them.