Another point made by Myko was to search birth date only. These were usually transcribed correctly, whereas names could be misread, and we all know where that can lead.
I had been searching for an aunt who was not with the family as expected, and using her name brought nothing. Using her birth date brought up a few, then I added her forename, resulting in two records, one of which was disregarded as there was a husband in tow. I thought about it for a little while before hitting the 'unlock household' but lo and behold, there she was, about 25 miles away working in an hotel. A transcription error, substituting a letter O for an S, changed her surname somewhat. Now I know where she was, but will never know why, and yes, I submitted the error report.