Is there any way to hide (not delete) selected polys or a cluster of a poly mesh? Seems basic enough.
Unfortunately no!
This has already been complained by many users.
Let
As a temporary solution, you can set your camera's clipping plane very close, like near 1 far 3. Not the ideal but still a solution.
The clipping plane solution has another advantage: components out of range will be ignored by selection and topology operations. In other words, you can't select what is beyond the view range.
Hope this helps
Salutations - Cheers
Bernard Lebel
Thanks for the info! Let's hope the lack is addressed in the future.
Micah Henrie
outr dreams come ture 
in 3.0 ,just hit H key after select faces,
it will be invisible!
thanks softimage!
and you can add a visibility property to a cluster...
so with the cluster selected go Get > Property > Polygon Cluster Visibility...