Let's ee.
Outside Fullerton 1, by the water, with tripod and a model.  Security guard came and gave me hell when a bunch of German speaking tourists were shooting happily everywhere.  Idiot said, photography is not allowed on private property.  I just wonder, do they also owned the entire promenade outside by the water?
In front of the Scarlet Hotel.  We are ON THE SIDEWALK, shooting a model.  Idiot manager came out saying that we cannot shoot the hotel.  Why not I said.  She said we might sell the picture.  So, it's guilty before the crime?
Chimjes, was there with another photographer, she is American.  We have 2 other friends, females, with us.  I got harassed and she did not.  One of my friend videoed the entire thingy with her mobile phone video cam.  We lodged a formal complaint to Chimjes management, she got a reply and I did not.  Nice going guys!
2 friends and I were shopping at one of the store on the ground floor of Paragon, one facing Orchard Road.  Together we bought enough to buy an L lens, and it's not the f4 varieties.  Friends want to take a picture of themselves in front of the display window. So I wiped out a PnS, took a few shot, and at the corner of my eye, a mad woman came out asking me what are we doing.  I said it's none of her business, call the police if she wanted to, and if she did, we would want to return everything we just bought.  She backed off.  I wrote to the company's HQ in the US,  got an apology.  But so what, there will always be a sour taste in the mouth.
This is my favorite one.  I was staying at one of the 5* hotel in Singapore.  I was a guest.  I was told, by another idiot wearing the hotel's uniform, that I cannot shoot the hotel lobby.  I ask why?  The answer was, I am using professional camera.  It was my 20D and my friend, she was using a Leica.  Oh well.  Of course, what do you expect DP to do in this particular instance.  I spent the next hour chewing more holes into the front desk manager, the duty manger and then the resident manager.  I was compensated, but I should have have to have this experience.
And then ...
Shooting a model in front of HSBC headquarter in Hong Kong, on the tram track, on a Sunday morning.  Police came by, told us to be careful, don't get run over by the tram.  
Shooting a nude outdoor in one of the gardens in suzhou.  Security came by and ask what's going on.  My mandarin is well, what mandarin. The 2 security guards knew what was happenning, we smoked a cigarette or 2 together, shoot went on, they kept watch, all went well.