Viewing Raw Vorbis Comment Data/Fieldnames Directly

I have a big collection of FLAC files, with tags that are, in some cases, pretty messed up. Inspecting a few files directly, one by one using Metaflac, I can see that the actual comment block fields vary widely from file to file, regarding, issues like capitalization, spaces, multiple entries for a given field name, random custom fields, etc.

I want to put all these files into a standard comment format. Using Mp3tag (to which I am new, and generally impressed), I can only see at the "tag" level. If I want to modify a field name, move data from a non-standard comment field into a standard tag field, or delete a non-standard comment entirely, it seems I need to know the field name defined in the comment first.

Is there a way to export all comments into a CSV format or something similar, so I can examine the entirety of what's in all these comments? Can Mp3tag allow me to view raw comment data directly ? Can anyone suggest another tool or workaround?

or am I missing the point entirely ?!?

thanks for advice