Noise by definition is unwanted; as distinct to signal.  Noise in business communication is costly - it can get in the way of intended messages and create confusion or concern in the audience. Inconsistency in what we say or how we say it is a very common source of noise in business. Policy, procedure, even pricing and product definitions suffer insidious inconsistency when left uncontrolled. This affects staff with uncertainty or inefficient distraction but the impact on external business relationships is more severe.  Inconsistency in what we communicate to customers, vendors or partners undermines our credibility. Where Dr Kirschner (author of the Art of Persuasion), warns about it in the context of political flipfloppery...

Consistency leads to the fulfillment of expectations, and we all want to be fulfilled. Inconsistency has the reverse effect. It leads to cognitive dissonance, which we the people find disturbing.

...it is a tenet of branding that consistency is king in making sure the experiences you create are associated with the impression and position you want to achieve. If reliability, attention to detail or intellectual strength are in any way elemental to your brand, you best pay extra attention to noise control.