I seriously think most of that comment was in fun humor, but yes Yorkie's can be difficult as other small dogs. However...I am a true believer that Yorkie's do get the hang of it.
Schatzie will be a year old in May and is pretty much potty trained, as an earlier post stated, 99.9% is where Schatzie is at. Dogs I don't think are ever perfect with this, accidents will take place with any breed.
However all the other great things about Yorkie's is what captures the heart. The devotion is unlimited to them in my opinion and those who own a Yorkie are very very blessed.
I hope you find the perfect pet for you!!