A good one I saw recently was a text file that, even though it had a .csv file extension was actually using another character as a delimiter (in this case colo

A good one I saw recently was a text file that, even though it had a .csv file extension was actually using another character as a delimiter (in this case colons) but as it contained large amounts of textual data actually had a enough commas to be parsed as a CSV file. VS Code and a suitable extension handled this rather better than Excel.