Hi,
Thank you for your kind words!
If betdrooms are taxonomies, you need the taxonomy filters, not the custom field filters. Custom fields (post meta) are different data structure. I believe this is what you are looking for.
For custom fields there are no sample values, as everything can be used. The values used are stored within the wp_postmeta database, and as far as I know the only way to get them is to directly check that database table.