Yes, call me stupid - I deserve it, but if this post helps one brother, then it is worth it.
I have had over 100 massages throughout my travelling career in Thailand, Indonesia and Vietnam. Never had any problems whatsoever but have always taken precautions.
The second day in the Phnomh Penh riverside area I went to the cheap massage shop (by memory think it was the one beside River Star Hotel). Fat mama sitting outside with two younger ones.
I am normally always very wary and careful by doing things such as putting my trousers/wallet on the table by my head, where I can watch them all the time, HOWEVER, due to my being tired/lazy and letting my guard down this one time, I put my pants on a table behind me - OUT OF SIGHT.
The very pretty young lady, unusually smiley and acting unusually sexy, massaged my front, then unusually asked my to turn over after 5 mins. I remember thinking this was unusual at the time. Normally you always get a good 20 mins on each side. She never offered any extra services (didn't need to, as she had just robbed me of $200 US).
I left the shop, saw the fat mama sitting outside, went to buy a drink. Handed over a 100 US bill and they said it was fake. Checked the other one in my wallet and it was also fake. My stomach sank. The worst feeling.
Obviously when she had asked me to turn over after 5 minutes, was when they accessed my wallet in my pants pocket and swapped my 2x 100 dollar bills with two fakes.
The massage room was small. I think her friend/sister might have crawled in on the floor and done the swap, because I really don't think my masseuse had time to search for my wallet and swap out the notes. They also might have had a false door in the wall for easy access to the table where my pants where.
What did I learn from this - NEVER let your guard down in a massage shop, DON'T take high US or large amounts in to a massage shop and DON'T go to the cheapest massage shops on the Riverside.

Finally, someone admits that they went for a massage and that they were victims of the old switcheroo rather than trying to claim that they received fake/Ghost money from an ATM. Good on you Doug Shitty thing to happen though, chalk it up as a tough lesson learnt.

There is only one hurdle and I'm not siding with anyone.

If you pulled out a fake $100 and tried to still buy a drink It's possible you could have received it anywhere.

Just a reasonable observation on my part if that's OK.

You've given me a good idea though. If I can get some fake $100 notes I'm gunna go and get a massage and throw my wallet willy nilly anywhere with fake $100's in it. That would be funny if they go to the effort of swapping fakes for fakes. Then the joke might be on me I'd probably be relaxing and getting a happy ending and I look down and they are using a fake hand on a broomstick.

The happy ending is for them.
They didn't crawl on the floor. There was a curtain behind the table where your clothes were. Never wondered why there's a curtain on a wall? There's a window behind that curtain

Go again and take a black plastic bag full of shit or a few mouse traps

Quote : Yes, call me stupid - I deserve it, but if this post helps one brother, then it is worth it.

I dont think it's going to help anyone, after all there are so many that have fallen for that trick in the past years and we still keep falling for it.

10 plus years ago I also got caught but lost my wallet as well as they probably did not have time to replace it back into my pants pocket. Luck would have it that us old age pensioners are so poor we only carry around a few riel in our pockets. I put it all down to a life's learning experience.