Appearances can be deceiving

[ralk]

Why appearances can be deceiving and not appearance can be deceiving?
From this http://dictionary.cambridge.org/dictionary/british/appearance?q=appearances I know that appearance can be used uncountably or countably.
What I understand is that "appearances can be deceiving" is about appearance in general so why not use the uncountable?


Also, these are examples provided by the web translator and how I perceive it:
You can change the whole appearance of a room by just lighting it in certain way. - uncountable.
There was nothing unusual about her physical appearance. - uncountable.
the large car outside the house gave the appearance of wealth. - uncountable.
Aside from the dashes, am I wrong about these?

 

[teechar]

Idiomatic.

 

[MikeNewYork]

In that phrase, we use "appearances" because we are not talking about a single case. It happens with many different appearances.

 

[Tdol]

It's a general statement. You could use appearance when talking about a specific case.