Whether you turn on Genius for Apps or not, the usage information's saved in your mobile backup. Perhaps in that case it's just not getting sent to Apple.

with enough responses, apple is effectively crowd-sourcing usage patterns (the usual error rates apply). so, if one app is getting reviews that are way out of line with the crowd-sourced usage pattern (when compared to other similar app's patterns) that might trigger a "lets go look at this one" flag at apple.