Extras piss me off and ruin the experience.
Like I have said in a few other topics I prefer the girl doing extras as it means I am guaranteed to get the service I want.
It annoys me when I see something down in a likes list or positive review for her etc. I go to see her and pay the £100+ wanting that service only to find she does not do it.
By saying she does this at £10 extra it means you definitely will be getting it.
Plus also it is a good ice breaker to get the service that you want. When you see a girl and you want something awkward and extreme like Watersports etc. Asking her for it can be a tad embarrassing/daunting.
There have been a few times I have not been able to ask as the girl was friendly chatty and nice and I thought I will look like a creep asking for this so went away after the hour not being able to even ask.
But while it being there for £10 extra. Its an easy, "so here's the £120 for your hour and the £10 for that extra". So in one easy swoop ice broken no embarrassment all dealt with at the start.