If you need to copy HTML tables into Excel, Libreoffice Calc or other datasheet applications, you can think about Firefox and Dafizilla Table2Clipboard firefox addon.
This addon will allow you to select rows and columns from a table simply pressing Control key and picking rows/columns with left mouse button. The selection can be copied to clipboard and pasted into datasheet applications but without ugly results.
Pasting in plain text editors is also supported as CSV file.
Here is the LINK for this great tool.
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