"My dog always uses these dog toilets when he passes by one. His favourite one was the at the end of the pier, near to the steps going to Po Wah Yuen, but that one has been dismantled. He still tries to locate it whenever he passes by that point. "
Absolutely ditto. My old chap always used that one and another one regularly, which is also now missing, I believe, near the construction opposite the animal welfare.
We get them trained to do these things and then they get confused when they are are not there. And let's face it, if you gotta go, you gotta go and if you've been holding it for the right location (aka public loo) no wonder they end up pooping on the path.