#18 probably someone who has dusty cleavage (it itches) rather than someone who is looking at it (whatever floats your dusty boob boat)

Not to mention the extremely unpleasant and unsexy accumulation of dust and debris in the cleavages, should the jackhammer-wielding female elect to expose her quivering décolletage.

As a woman who has used a jackhammer in the course of my professional duties, I would have to say no, no, no. A bounceless-as-possible sports bra is key.