I think that it would be unusual to have a WG achieve an orgasm, particularly on a first meeting.
Personally, I tend to stick to the same few girls, so, yeah, they do sometimes orgasm.
One in particular, a filthy mare, will orgasm easily, whether by mechanical or penetrative means. I know she's not acting as I've done MMF with her and her partner, for which I did not pay as she considered this to be swinging; so I guess there was no incentive for her to 'pretend' with us.
Mostly, I'd say the 'orgasms' are faked. Who cares?