There are a few instances where you "wont know till ya try it yourself"... but they're few and far between with proper research.
I think it really speaks to the expectation of developers here that users are expected to "gamble" on app purchases without knowing whether the app is good or not by reading reviews, and general consensus. Thats a really exploitative purchasing pattern to expect from your users...
Not saying there arent plenty of dumb people to pray on, but... yea.. wow. A lot of app store developers here on HN just expect their users to be dumb ill informed "johns" to exploit for a dollar on a gamble... That really says something.