Static (Noise)

There are people who loves to move their body to the music, swinging their arms, etc.

Well, this is fine is you are not leading.

As a lead in partner dance, even a flick of the wrist can be a signal to the follow.

Thus excessive movements would make it confusing for the follow to pick up which is actually a lead and which is not!

It would take a very experienced and fast follow to be able to read leads that have too much unnecessary movements.

I personally advocate that leads (for salsa) keep their arms and wrists relatively still (note that 'still' does not mean stiff) while not leading any moves (e.g. when doing basic). The results are very obvious.... there were many many follows who complimented me for being very clear in my lead and easy to follow, after their 1st dance with me.

On the same note, one VERY common mistake that leads make, is to 'row' their arms while moving :) They might think it FEELS cool but most don't realize it can LOOK comical if not done 'properly'. (Many Cuban style movements rock their arms in a way but that is a separate story)