Naruto Shippuden Episode 35

[iMUSTbeTHEdevil]

Maybe sai just likes seeing the reactions people make, considering that he himself is devoid of emotions.

So you are saying that he is a typical teen hellbent on shock value? Sounds like any artist of that age that I know. Works for me.

[DarthEnderX]

I think he does it to prove what terrible ninjas they are. If Danzou controls root and he's "emotionless and logical" then Sai probably is too.

And by insulting them he's proving what shitty ninjas they are compared to him by showing how they let their emotions control their actions.

[Killa-Eyez]

It kinda is my idea of a real ninja though. Not even like Sai, cause he's socializing to much and having a opinion. But real ninja's are trained to do what others aren't capable of, physically and mentally. So the no emotion, logical attitude is fitting for what they're meant to do. At least that's my idea. We obviously see a happier side of ninja's (which is unlikely) in Naruto, but it seems that Root is producing more ninja-like ninja's then the others I've seen in the series so far. When Sai was in his room with the other Root member I kinda felt that long lost sinister ninja feeling...

[Buffalobiian]

The "devoid of all emotions" part may be a common aspect amongst all the ANBU departments, though variation is bound to occur. We've been pretty much lead to believe that these "masked shinobi" do all the work that you'd not want to be recognized for. The expressionless masks also lead us to believe that they're the more emotionless, indistinguishable, stereotypical ninjas, though their mission success rates have shown otherwise.

I was more focused on the other stuff they Sensi said to Sai about root, how they're unseen, underground and forever supporting the great tree known as Konoha. Drilling that stuff into you makes you feel your actions are correct in every way.