"....So I guess we're reading a lot of pages from the large IO pool but very few of them."
If you meant to say that "we're reading a lot of pages into the large IO pool, but actually using very few of them".....the answer is "Yep!"
PagesRead is the number of pages actually read into cache....or if you do:
select * from master..monTableColumns where TableName='manCachePool'
You will see the description is:
"Number of pages read into the pool"
....now the indicators column suggest it needs to be delta'd - and looking at some code I wrote, it appears I was incorrect earlier and PagesTouched does as well.....so unless you had rollover (PagesTouched hit 2B), then you are in even worse shape than you thought. Sorry about that - I was answering in a hurry earlier.
However, remember that any sample is just a point in time ....there may be cases where the entire cache is used. Hence you should watch this over a period of a full day or a full week and baseline it.