My view is if a wg charges extra for something simple she doesnt enjoy it!
That's my inclination too, with the more 'regularly accepted services'. I wouldn't pay extra for anything and I can't say I'd enjoy it knowing that she probably doesn't either. Mind you, some may get a kick out of that.
Perhaps a little different if one is veering into BDSM, water sports or scat, no doubt.
But then again one man's 'normality' can be largely different from another. I can't understand why anybody would pay extra for kissing, oral without or fucking?