Walking out

Is it wrong to walk out of an appointment that is going to cost £300 per hour when they look nothing like the person in the picture?

In mean I feel like you make an agreement on the amount knowing what you're getting. And if it's completely off I don't think you should personally have to go through with it. Obviously don't be horrible but we should be honest if we're expecting the same in return. That's my opinion :)

Not at all.

You have every right to not go through with it if you have a case of false advertizing. The point of no return is the handing over of the money.

On my two bait-and-switches, the first was actually gold-star and the second was a situation where I had already blown her off once but I would encourage everyone to not encourage such behaviour my hypocrisy notwithstanding.

Regardless of the price, it is perfectly right and acceptable to POLITELY leave if you are not happy once you walk inside.
It's not just the appearance of the woman, there are many things that could make you feel uncomfortable so leave.

If you aren't confident enough to be honest, you can try the familiar lines that go:
"I just realised I've left my wallet at home"

We all know what that means.

It's awkward to walk out but really its the right thing to do if it is bait & switch, otherwise you are encouraging that kind of practice. There is always a risk that profile pics are fake.

I've had it happen twice. The first time I should have walked but didn't. The second time the girl was surprisingly much more appealing than the one in the pictures. Maybe she was using a friend's profile.

But if I had to walk I would simply apologise and say I've got to go. You don't need to explain yourself to someone who has tricked you.