Dog Health Questions: Different Dog Training Methods in the same home?

I am looking at getting a puppy very soon. My room mate already has a 2 year old dog of his own. He taught his dog the basics using a reward/punishment training method. She has developed some bad habits such as jumping on couches that frankly don't bother me but things I would not want my dog doing. I have been researching clicker training and plan on using this method. My questions is whether his dog's bad habits will affect my puppy's training. Will I be able to effectively teach my puppy not to do the things his dog is doing or would it be a lost cause?

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The fact your roommate's dog jumps on the couch has nothing to do with the training method he uses and everything to do with what rules and boundaries your roommate has put in place.
It is not his "method" that allows the dog on the couch, it is your roommate. If your roommate had trained properly, the dog would not go on the couch if he was trained not to.

Yes, you can both use different training methods.
It is going to be very difficult to teach your dog not to get on the furniture unless your roommate is on board. If he allows your dog sometimes, then it is going to be that much more difficult for you to reinforce the idea he can't.
It is also going to be harder because your dog may follow some of the behaviors of the other dog, and try to get onto the couch, particularly since you are choosing not to correct him.

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• dogs take cues from others around them, so he will initially want to be on the couch.
  
  you can train your dog to stay off furniture using clicker methods. HOWEVER, if the roommate doesn't follow through as well, the dog will learn that he is allowed on the furniture unless you are around. This won't solve the dog-hair-on-the-furniture problem, but may be enough for you.


• It is going to be very difficult to teach your puppy not to do things it sees the other dog doing. Puppies tend to learn a lot from the other dogs they live with. It would be better to see if your roommate will let you work on correcting the other dogs bad habits before you get a puppy.


• It might, but if you train it well, I doubt any other dog's behavior will affect how well your dog listens and what he does.


• For a dog to jump on the furniture, is a sign of dominance.
  Your roommate has caused a huge problem here, with the lack of proper rules & boundaries.
  
  Your roommate has done it all wrong, and you have the correct idea.
  
  Your roommate allows his dog to get away with it (wrongly), and that dog thinks it is dominant.
  When you teach your dog to stay off the furniture (rightly so), it will make your dog learn it is submissive - as it should.
  
  Yes, it will create a lot of conflict between the 2 dogs. Your roommates dog will "lord it over" your dog and constantly try to force your dog to submit to it, even so far as to take your dog's toys & food. Your dog may resent that and become aggressive.
  
  I can foresee a lot of behaviour problems with this arrangement, unless you & your roommate agree to have the same rules & boundaries for both dogs, and both start teaching your roommates dog to stay off the furniture for a few months before you bring a new puppy home.