It really depends how you define"fake". I've found that around 50% don't reply at all, I guess you can't get much more fake than that.
Of the rest, some proportion are time wasters who go radio silent after you've turned up for a booking. I'm guessing that's mostly down to them not caring if they double book, since they're not really after repeat custom.
Of the remainder that you actually get to see, maybe half turn out to be a totally different girl to the pictures. For the rest, the pictures are either heavily shopped, or from a good few years back, or both. It's a rare occurrence to turn up and think "wow, your pictures didn't do you justice".
Then even if you've managed to turn up and actually see the girl you're expecting, it's pretty rare to get the service you were hoping for. Most of them seem to treat the profile text as a way to lure guys in, and don't believe it needs to bear any relation to reality.
Yet despite all that, some of us still spend our time and money pursuing the holy grail of an attractive young hottie who provides a decent service for 15 minutes for a mere £40. It's bloody gratifying when you find it too.