Most of the records we deal with are handwritten. We've already discussed being open to different spellings of your ancestors' names since those writing the information rarely asked, "How do you spell that?". These records are then transcribed or indexed to make them searchable online. That involves someone looking at the record, deciphering the handwriting and typing in the information. So let's see...
1. No concern for spelling
2. Indexers deciphering handwritten records
3. Data entry typos
It's a wonder we find any of our ancestors!
If you find a record has a few things in common with the person/family you're looking for don't dismiss it based on the differences you find in the transcription. When it's possible, take a look at the original record for yourself. There's a reason Ancestry.com allows its subscribers to submit alternate information.
The record linked below has been corrected since I bookmarked it to use as an example and the original transcription is listed as alternate information. (Links go to Ancestry.com for those of you who are subscribers.) There are other members of all these households but I've only included a few names here.
Head of household Ann May, born abt 1870
Mother Missouri Blackard, born abt 1912 in Nova Scotia, Canada
More after the jump.