Well I learned something new today. I was able to trace one of the SQL Agent jobs to an old report that was setup with the option "Render this report from a report snapshot" using a report-specific schedule.
In the Processing Options in Report Manager I switched it to "Always run this report with the most recent data" and "Do not cache..." then clicked Apply.
I refreshed my list of SQL Agent jobs and the one for running this snapshot was gone!
So a question I have now is, is there a way to tell SQL Agent jobs for snapshots from ones for subscriptions?