I advertise as naughty GFE so I know that I'd lose a whole lot of custom if I didn't offer owo, dfk, and/or cim, I'm not into long periods of shagging without stopping so I feel my owo+cim make up for it, plus been in the job a while so my oral is worth sex being missed out on, haha, blowing my own trumpet but hey ho!! :+) ;-)
IMO owo+dfk are just 2 services that a GFE must provide, I'm sure some will disagree but we all know that we're all very different in our services, attitudes, opinions, etc,etc.