I called her and arranged a couple booking a couple of weeks ago when she was in Watford. She sounded nice and actualy eager for a threesome.
We had to cancel last minute and she was ok with that.
Now I know this doesnt exactly answer your original question, but I tend to see it as a good sign if they are keen to meet a couple, for a couple of reasons
1. If I am with my partner I am less likely to have any issues around being discrete, so therfore my bargaining position becomes a bit stronger
2. If I arrive on my own and its a B&S, there is a good chance I will think with my cock and accept whatever.
3. Women are more critical and if we arrive and she hasnt made the effort to look nice, men might think 'any holes a goal' women/couples are more likely to walk, and just go home and have sex with each other
Its funny to hear the tone of the conversation change when I call and say, "is it ok if I bring my partner?"
Not only did she sound keen, she also said (without me proding) "I do not charge anything extra for couples both of you for one hour £100"
I would consider her legit from the phonecalls
Hope this helps a bit