Lyric discussion by SongInterpreter 

Cover art for Blue lyrics by A Perfect Circle

First of all, allow me to say, it is "optimist".

The song is about finding something new about someone, noticing a sudden change in someone, or or being deceived by someone, which repulses you/him. This is why he says things like ignore the smoke. Just act like he never knew, the smoke was never there, he never found out.

He's saying to call an optimist because in the situation he is not optimistic. He has no faith in it.

People generally jump straight to "drowning" figuratively or metaphorically when someone turns "blue". Truth is, they are turning "blue" because whatever he found out is killing her. Its ruining her in every possible way. Not only for herself but also how he viewed her and now he cant ever look at her the same.

The lyrics reference which substaintially agrees with what im saying is that he says "Such a lovely color for you". Basically saying, "Sure, go ahead, great idea." or "Who am I to stop you from doing what you want, I had to find out like this, right?". Basically just letting it be because hes so disgusted he just doesnt care anymore and hes quite sure, pestimistic, that it will not ever be the same between them.

When he says, "Mistook their nods for approval", that was actually speaking for her, and she just assumed he was ok with it, or not bothered, and she went and continued. So he ignored how aweful it was, never confronted her, and just smiled like everything was perfect.

Song Meaning

@SongInterpreter i hadnt figured out what the line "Mistook their nods for approval" meant, i liked reading an idea of it. good interpretation :)