1.Inconsistent formats of data within a row or column which results in confusion and difficulties in making sense of the data
2.Wrong order of columns
3.Inserting different types of information in one column
4.Missing data in row or column
1.Dates all in different format: Month/date/year and others as date/month/year
2.Total before units or price
3.Dates, units, price all in the same column