i am korean and i live in korea.  I have seen videos of them preparing cockerspaniels.  Is a cockerspaniel not a pet dog.  There is no special bred dogs.  Even if they are not pet dogs have you seen how they are treated and how they are shipped around.  Its not humane.  I am not an animal rights activists at all but some things are just wrong.  And do you know how they slaughter the dog?  You should look up on youtube.
Just going to Moran Market you will see dogs being sold and caged, its blatant and still going on today.  They also believe making the dog terrified then beating them to death makes the meat taste better. 
With this being said.  All koreans do not eat dog.  The dog eating population does not represent the whole population.  Just because some americans eat rocky mountain oysters doesn't mean the whole population does. 
Koreans are not the only culture that enjoys dog meat either.  Look at all these countries who have been known to eat dog meat. 
Dog meat - Wikipedia, the free encyclopedia
Koreans just seem the ones that are picked on the most about it. 
But having lived here for quite a while and having a wonderful dog.  Korean people do not think of their pets as americans or westerners do.  And they do not understand why we love our pets so much.  The younger generation does appreciate and understand our love of pets. 
For example some people would make comments about eating my dog as a joke then they add "yeah but he wouldn't taste that good, doesn't have enough meat on them bones."  Who in their right mind would say that about your dog back in the states.