Is there a way to do text substitution within fields in Views?
Have a look in your view under Advanced -> OTHER -> Theme: [Information].

You'll see each field can be themed separately either across the board or in a set of themes, or on a specific theme, pick whichever file name best suits your needs and add a new file to your theme's template folder with that name.

You can use the link on the field name in that window to grab the default starting point for that field and then edit it.

Once you've created the file and put the default text in it, start playing around with preg_replace(), this uses regular expressions to replace certain characters.  Here's a starting point, it replaces hyphens and underscores with spaces in the $output variable (I think. My regex is a bit shaky):

preg_replace('/-|_/',' ',$output);