When one attempts to place water on (or beside) a fence or a sign in the Nether does not show smoke particles. Although it works properly with almost every block that I have tested- anvils, iron bars, half-slabs, etc. the only objects which have this issue are every type of fence and the only type of sign.

Interestingly, when you crouch and try to place water on the fence/sign, the smoke particles DO display. This may mean that the fence (and sign) are treated like an interactive object in this sense, so one cannot accidentally place water while opening up a chest and such.