In my reading (and experience), if the crust is wet when the next layer falls on it, then the bond will be initially be good. If the crust is dry, the bond will be poor (and you will be able to tell when skinning..it'll be like skinning on ball bearings.) (see Tremper page 123)
In my book learning, I have read the following as well: In the shorter term the most worrisome change that could ruin an initially strong bond is "melt layer recrystallization." In melt layer recrystallization, a strong temp gradient between the warm, soggy crust and new snow facets layer immediately above the rain crust. In the longer term, I think that crust can act an "inflection point" in the temperature gradiant, leading to faceting immediately above and below the crust as well, over a longer term. (Tremper page 128)
