All over the world, South Asians get a bum rap for being equivocal. This comes from the Occidental's inability to understand head movement. It is as simple as that.
They claim that we nod our heads to say 'no' when we mean 'yes', and 'yes' when we mean 'no', or at the very least we try to fudge the issue by making a vague gesture that signifies negative nor positive.
There is actually no cause for confusion, which only exists inside the head of overseas observers. For them, there are simply two kinds of head movements, those that indicate 'yes' and 'no'. They cannot countenance a third category of movement, which has very subtle shades of meaning that tilts from 'okay' and 'maybe' to 'if you say so'.
With this third type of head movement, the subject is not trying to equivocate or confuse, but is instead seeking to indicate a nuanced sensibility which understands that the world is not made up of blacks and whites, but overwhelming greys. Most importantly, this head waffle (as opposed to the nod and the shake) is a wholly different species of head-movement and not a lame South Asian mid-way gesture between the two.