I think this is a great topic because as a client you should actually think through what you will do in different situations before they occur. To me it depends on how egregious the misrepresentation is.

If it is just the pics are older and she has aged or has gained weight, I would probably go on with the session since I generally do research and the things that get me to book go beyond looks.

If the misrepresentation is that she stole someone else's pics and rep and tricked me into showing up or that "She" was actually a man (which is extremely different from a Domme who openly advertises as a TS), then I would GTFO as soon as I could... using whatever I felt was necessary to get out of that situation since I have no idea how much danger I could actually be in.