After turning on Send Scheduled Reminders and setting up a Membership Renewal Reminder, why am I getting all zeros in my Scheduled Reminders log?
You say you get the feeling...have you gone into Search > Find Activities > Activity Type of "Membership Renewal Reminder" to see what it lists?  I always check to see if it has recorded the activity.  That doesnt mean it has been emailed only that it was scheduled against that account.  Additionally my reminders show up in the Recent Items on the left side of CiviCRM.