That's not a pug that's a Shar pei. They're fighting dogs and much larger in size - how did you get this confused?
[image/]http://www.greatdogsite.com/admin/uploaded_files/1191990601pug.jpg[/IMG]
A Pug.
Both breeds are supposed to be quite stubborn, Shar pei are larger so I imagine previous experience with big dogs is essential and Pugs characteristic squished nose can cause them breathing problems (I heard from a helper at school that they are spectacular snorers

). I guess like any dog they just have to be well trained and cared for and you have a loving family pet.