Yes, to be a good genealogist you need to be a copycat. Each of us must be able to accurately transcribe (copy) what we see on a document!
It's crucial to write down (copy) exactly what is on that document, not what we THINK we see, or what we EXPECT to see, or what we HOPE to see, but what IS ACTUALLY THERE.
That means if you find Great grandmother Sadie in a census but her name is recorded as SADY, you should copy it EXACTLY as it was written originally! It's okay to make a note that Great Grandma wrote her name as Sadie on every single record you've found other than this census.
If you find your auntie Sybill in the census but her name is recored as Cybell - copy what you SEE not what you WANT to see! Yes, the census taker probably spelled it incorrectly. But far be it from us to change that original record.
If the record is indexed incorrectly that's okay to ignore that. You don't want to carry on an error made after the fact. When you find an incorrect index entry, check the original and copy what you see there. When viewing an original record, be careful to copy it accurately.
You found Grandpa Charlie in a document. You know it's him but his name is recorded as Leon. What the heck?? If you proof that this is indeed the man you knew as Grandpa Charlie, as a good genealogist you will copy EXACTY what is there (Leon) but make a note that perhaps Grandpa Charlie had two given names (Leon being one) or perhaps Charlie was just a nickname. The important thing is not to alter what is found on an original record. (by the way this is a true example from my husband's family - a grandfather christened with the name Leon Thomas but called Charlie his entire life)
Being a copycat also applies to your genealogical correspondence. One of my pet peeves is hearing from other genealogists who mis-write my name. My name is Lorine yet I often receive emails from people addressed to "Lorraine" or "Lori".
Neither of those are my name. In fact Lorraine isn't even a mis-spelling of my name, it's a completely different name completely! My name is on the bottom of every email I send out. It's on all my websites. What does this say about the genealogist writing to me? That they cannot copy correctly, that they write down what they EXPECT to see (Lorine isn't a common name), or what they THINK they see... I often wonder how accurate (or inaccurate) they are when copying down records pertaining to their ancestors.
We all make errors sometimes. A slip of the pen, a lapse of concentration and we've changed what was on an original record without meaning to. And that is why it is wise to double-check and triple-check your work.
Be careful, be a copycat, and be sure you are writing down what you find, not what you expect to find.