Oppai has good intentions (and is a gentleman) and I would do the same if I am booking with someone reputable in advance.
However, with many last minute bookings and craigslist advertisers I am finally getting comfortable with walking out if I am not happy with what I see. I used to TOFTT and feel miserable and ripped off about it. I then started to tip a 20 and politely decline services. Now I politely say sorry, "you're not what I was expecting" and leave.
I think turning around and leaving is good for the smaller incall places. I don't expect real pictures but at least something that is slightly representative or at least within 5 years of the advertised age would be nice. Yes, by walking out one would waste the SP's time, but they should also take into consideration that pooners can spend an hour in travel, take time off work/families/friends, pay for parking etc. as well.
The Keg example is good. If I order a steak and its not made to my liking I might politely say something. However, if I went to the Keg and all they had on the menu was Tofu WTF should I have to stay, order, eat it and pay for it?
What a complete waste of my time.