Sometimes I love these threads and sometimes I hate them. A WebmasterWorld thread asks if he will negatively be impacted by adding the noindex meta tag to 3,500 pages on his site.
The answer to these questions is never black and white. It depends.
(1) By adding the noindex meta tag to the page, you are saying you don't want those pages indexed. So yea, you don't care what happens to these pages.
(2) But can it impact other pages? Sure, Google will stop indexing those pages and any internal linkage the pages you want in the index might be degraded a bit or might not.
(3) PageRank will still flow to pages that have the noindex meta tag, so keep that in mind when trying to control your PageRank flow.
But if the pages have yet to be indexed and you want to keep them out, then I doubt it will hurt. Plus, if there are no real links to those pages or if they are all nofollowed or canonical tagged off to another page, then you should be fine.
These types of questions always "depend" on so many other variables.
Forum discussion at WebmasterWorld.