If you invest any time maintaining the quality of your database, do NOT refer to Smart Campaigns in your programs or reports because Marketo's latest feature of not auto-refreshing the campaign members will throw all your numbers off, as we just learned the hard way.
By not refreshing automatically, reports that refer to Smart Campaigns in the smart lists will use the older, cached numbers and properties, thus resulting in very inaccurate numbers.
Be sure to go in and manually refresh every Smart Campaign that's referred to in a report before generating the report.