For me, of course the issue is not whether the cabbies feign ignorance when I call him a name (I do want him to take me to my destination and not kill me!) but whether the cabbie knows I'm not from Shanghai and takes advantage of me because of that. If you clearly look foreign, there just isn't much you can do to prevent being taken advantage of. Sure, you may have the hotel sort it out if your hotel is the final destination, but what if you are taken to a tourist site? What do you do when you get to the tourist site? You call the cabbie a name and then what? Engage a local to help you? It's just all a hassle... and unfortunately a part of the tourist experience, trap and all.

My experience has been the exact opposite of op. Shanghai = ok. Beijing = take advantage of you. Maybe that's because Beijing has more tourist sites. One cabbie claimed that forbidden city only has one entrance and he has to take me to the other side for me to get in. Thankfully, a Beijinger friend was with me...