Relationships Referred by and Referrer are confusing. We need better names but we have what we have for now. Since we consider referring someone a significant indication of engagement and a very advanced pipeline thing to do, we want them to be right!
I wrote a report that finds all these relationships and sorts them by the difference between the day the original contact was created compared to the date the referred contact was created. This was implemented with a row level report.
The assumption is that the referred contact is newer than the contact that did the referring. So all relationships that are negative appear to be backwards.
We have a contact lookup setup to create automatic referrals. We should test that the referred by field created automatic relationships with the proper sense.
The report was added to the Wall of Zero II Dashboard which comes out monthly. It could be possible to implement a similar check as a validation rule or pop-up window in future. But for now, monthly cleanup will likely raise awareness so that things stay cleaner.