I had already done that, but that doesn’t pop out any typo duplicates or syntax goof ups.
I was hoping for a big list of unique labels sorted alphabetical. With standard functionality of a link on each label to filtered hosts or services using specific label, so you can edit them at specific host or service configuration.
If there isn’t such a place, then thinking outside of the box… 
Maybe inspect what sources the autocomplete in the filter uses, perhaps this information is stored somewhere in OMD.
Or alternatively I can go for an all host view and try to alter the view with user styles so only the labels remain.
Options to investigate tomorrow.