What’s the most frustrating part of cleaning messy Excel/CSV data?

I’ve been working with a lot of messy spreadsheets lately (duplicates, inconsistent formatting, mismatched columns, etc.), and it feels like everyone runs into slightly different issues depending on their data.

Some people rely on Power Query, while others do things manually, but I still see workflows break when the data isn’t consistent to begin with.

Curious what tends to slow you down the most when cleaning or organizing data?

Is it duplicates, formatting issues, inconsistent columns, or something else?