If you are using thunar as mentioned in post #6 then gsettings / dconf won't help you afaik
There is a somewhat parallel settings mechanism called xfconf, it shows a parameter called /last-show-hidden
If you monitor it while toggling thunar's hidden file visibility (via Ctrl-H or the View->Show Hidden Files checkbox) it appears to be the relevant parameter
$ xfconf-query -c thunar -l
but although setting it seems to be allowed e.g.
$ xfconf-query -c thunar -p /last-show-hidden -m
Start monitoring channel "thunar":
it does not change the active display i.e. it seems to just be a record of the 'last' toggle event as indicated by its name, rather than an actively updateable setting like the dconf/gsettings equivalent.
xfconf-query -c thunar -p /last-show-hidden -s true