If you are looking for unusual conditions, scanning through visually is sometimes easier than it would be to try to grep for the particulars of an entry, especially if you don't know the particulars of the unusual condition yet.

Some editors with "minimap" functionality (Sublime Text and Emacs that I'm aware of, maybe others) can give you a fairly good visual overview of large swaths of a file at once. Sometimes strange entries are obvious just because of the shape of the line and in those cases the minimap makes it easy to see when something unusual is happening.