I did this today when I could not find Ranslow Smith (1805-1875) in any US census from 1850 to 1870. The reason was simple - he is "Rauslow" in 1850 in Dodge County WI, he is "Rauslon" in 1860 in Dodge County WI, and "Ronsle" in 1870 in Taylor County, IA. If he had lived longer, I'm sure the name would be wrong in the 1880 and 1900 census records too!
Here is what I did today for the 1860 US Census entry. Here is the search result for Ranslow Smith:
In the left column is a link for "Comments and Corrections." I clicked on it:
The page above permits the user to correct Misspelled or alternate Names, Add a Comment, or Report an Image Problem. I clicked on "Misspelled or Alternate Names:"
On the page above, I added the correct Given Name and Surname, then clicked on "Transcription Error" from the dropdown menu of choices (the other choices were Incorrect Original, Nickname, Birth/Maiden Name, Name Change and Variation).
I wrote a short note in the Description box explaining why I think the name should be Ranslow and not Rauslon:
Finished, I clicked on the orange "Submit Correction" button and received this message:
It says that the correction will be added to the Search Index in a few weeks, and the little yellow triangle indicator thingamajig should show up on the result page shortly. Note that this will add the name "Ranslow Smith" to the Search Index and will not replace the "Rauslon Smith" name in the Search Index.
I did all of this in the "Old Search" because of the "New Search" problem I highlighted yesterday in Ancestry.com Quirk - Different Results for Old Search and New Search.