How can I tell if a user came to a page via a Google Adwords PPC campaign?

Question

I have a form with a hidden "Came from Adwords" field that will be marked true (via javascript) if the user came from a PPC campaign and will stay false if not. That way, when the user submits the form, we will have each submission stored with info about whether that submission came from adwords or not, all without the user knowing.

How can I fetch this info? I know that Google sets a cookie called Conversion whenever you click a PPC link to a page, but the cookie's content is just random alphanumeric characters. Is there something in the Analytics/Adwords API that will let me test for this? Do I have to resort to adding ?ref=adwords or something onto the PPC URLs so that I can test that way?

Answer 1

Old news, but look for the glcid param on the URL if you've got AdWords autotagging enabled.