On ServerFault someone was asked a question why .csv files were unable to be viewed in Quick Look. For some reason .csv files are not defined as plain text by the operating system which leads to odd conflicts between applications that can deal with .csv files that causes QuickLook to report that it can’t find a generator for the file and just show the icon.
The one way to force it to work is to roll your own, with a bit of help after reading the QuickLook Programming Reference it was rather simple to roll together a proof of concept QuickLook generator for .csv files.
It’s not pretty, it may break at any time (if only because it’s using a dynamic UTI since one is not defined anywhere, however .csv files have been using the UTI “dyn.age80g650” for quite a while - as far back as prior to 10.0) but it works and forces the .csv to display properly.
The code and a download of CSVQL is available on GitHub:
Check out Pascal’s comment for a much nicer looking version - actually puts the data into tables.