How to add additional spaces around dash?
In order to get better readability for a filename like "Artist - Title", you can add spaces so that it reads "Artist - Title"
Create a new action in an existing action group, choose Replace as action type and enter (without the quotes):
- Field: _FILENAME
- Original: " - "
- Replace with: " - "
You can activate the action group via Convert, 
Actions and apply it to the selected files.
Unintended duplication of spaces can occur, if you're executing this action several times. "x - x" becomes "x - x", and "x - x" becomes "x - x" etc. You can prevent this by adding a second action that makes " " (3 spaces) to " " (2 spaces).
It is even more simple if your files are already properly tagged: you can use the converter 
Tag - Filename with the format string "%artist% - %title%" and get the same result.