TravelinWilly - sorry to read your story.
I found this recently on the Internet, forgot where:

".....I love Buenos Aires but I am one who had mustard/mayo combination sprayed on
mine and my wifes clothes while the man and woman who "spotted it" and
called it bird **** tried to wipe it off ( they were actually picking my
pocket). A third man was offering "agua" just around the corner to assist
in getting more of it off our clothes. Meanwhile, before we discovered the
pick pocketing, the couple had to leave and my wife was thanking them as
they dashed across 6 lanes of traffic to catch a bus. I suspected what was
happening, checked my pockets and while my wife was talking to "agua man" I
dashed after them. My wife saw me catch up with them just as they hit the
sidewalk and assumed I was going to give hem a tip. She couldn't understand
why I was shaking the man. But then he led me back to where my wife was and
removed my money clip from under a post office box, all the while
apologizing profusely. The 3rd person with the agua was simply trying to
get us away from the site so one of them could return and pick up the money
clip after we left. A lesson well learned. It happens in any large city,
Rome, Mexico city , Guadalajara etc. Gotta keep your wits about you.
Mexicowilkie...."

We met a German couple at this old café in the city center of Buenos Aires. They also complaint about a ketchup attack.

[This message has been edited by USAFAN (edited 05-21-2003).]