What is Patchy ?
Patchy is (adj) 1. not the same everywhere If you don’t prepare the surface properly, the paint will look patchy. 2. sometimes good and sometimes not good This year’s exam results have been patchy. 3. occurring in some places but not in others There may be some patchy rain in the southwest. (NOTE: patchier patchiest)
source: Easier English, Student Dictionary Upper Intermediate Level