Why is Adwords Keyword Tool showing zero search volume for popular keywords?

[nicole.healthline]

When I try to ascertain search volume for the the words "pills" "drugs" and "medicine" it is showing "-"  for all types of search volume, including phrase, exact, and broad. Why is this?

[GroupM]

I had seen the similar results when I try to search for popular keywords like college. The thing I noticed is that there are not a lot of people searching for college exact match (they usually search for college + information about the education or location).

I think you have the same problem as I did. The easiest way to deal with it is to use the SEOMoz Keyword difficulty tool, because that way you will get clearer view of the whole picture. Also I recommend going for longer and more specific keywords since this will ensure more conversion oriented traffic from the search engines

Hope this helps you. If you have any other questions, please do not hesitate to ask, but make sure you mention the market your are targeting

[Daylan]

Odd. . . 
I thought it might have something to do with spamming as these are heavily spammed terms (same results don't show up for Viagra either). But then i found this post, which a google employee is asking for examples. Sounds like a problem more than a 'feature'.

http://www.google.com/support/forum/p/AdWords/thread?tid=4930bd33634b1755&hl=en

[JamesNorquay]

Are you getting these results when logged in? Or logged out of you Google account.

I have found that some times you see crazy data when you are logged out, yet when you log in the data seems a lot better.