Welcome to Android Central! The fact that the paint is scratched wouldn't affect water resistance. However, it would be hard to know for sure what kind of abuse the phone went through prior to being refurbished. If the phone had any kind of trauma that led to even a tiny break in its integrity (like a little crack at the edge of the screen that might be hard to notice), it could increase the risk for water damage. I don't know if the refurbishing process pays any attention to maintaining water resistance.