When Geooh obtains detailed log information on a geocache it reviews the last log to see if it was a DNF or a note. For a DNF, the icon will show a red DNF overlay on top of it. This is a useful feature to quickly see which geocaches in a list or on a map may be lost. It gives you a chance to inspect more logs or details about the cache before taking the effort to drive to it and search for it.
Only in Geooh!