B.F. Skinner is doing the happy dance in his grave right now over this discussion.

Since we are talking about changing behavior, 'positive' and 'negative' can be somewhat unnecessary and totally confusing in defining what will and won't change behavior. Basically, all those two words signify is the adding (positive) and taking away (negative) of a stimulus. At times, the same exact stimulus can qualifiy as either positive and negative, and can even more confusingly, can be so at the same exact time- such as when a person suffering with OCD goes through the ritualistic washing of hands 50 times (the positive/addition) to alleviate the obsessive compulsive thoughts (the negative/removal). As is obvious, the hand-washing is both positive and negative at the same time. Many behavioral psychologists discourage using such qualifiers due to the debatability of the terms. If those terms are used at all, they are more likely to be applied to punishment rather than reinforcement.

The key to behavior modification, as is purported by behavioral psychologists, lies within reinforcement and punishment. It's most appropriate to see both these included within this thread. These terms are neither synonymous nor opposing. Rather, the terms denote differing ways of changing behavior. Simply put, punishment will tend to decrease the future occurrence of certain behaviors and reinforcement tends to increase the likelihood of certain behaviors repeating themselves. I mention both because not all resolutions of a problem come from the decrease of a behavior. Sometimes an increase of a particular behavior is what is necessary to make things better.

If a Dominant, or submissive for that matter, wants to eliminate or decrease the incidence of a particular behavior, then punishment will be the way to go. Perhaps a Dominant doesn't like that his submissive curses. She knows he doesn't like it, but the language is so ingrained from years of mis-use, she slips up frequently and out comes a "hell" or "damn". What the punishment should be would probably best be determined by what the punished one would respond to more deeply. Maybe she'll respond more effectively to a positive punishment (such as adding an unpleasant chore or task to her regimen). Or maybe a negative one (the submissive is removed from her Dominant's presence for a set amount of time each time she curses) will do the trick. I am of the opinion that both parties involved should determine what course of action would affect change the best.

Now if a Dominant, or again, a submissive, wants to increase the likelihood of a behavior repeating, then reinforcing techniques (think the bell in Pavlov's famous experiment here) should be used to achieve the desired result. Say the Dominant wants his submissive to greet him in a specific position each time he enters a room, but she is having trouble recalling to do so. A reinforcer, such as a pleasedly uttered "good girl" (positive) when she assumes the position, or lack thereof when she doesn't (negative), should be put into effect. Again, to figure out the best course of action, those involved should work together on the plan.

So depending on what's desired, punishment or reinforcement can be utilized. As was also mentioned, each person is unique, so no one thing can be used as an all-effective punishment or reinforcement across the board. But used properly and thoughtfully, either can probably produce necessary and satisfactory changes in behavior.

Edit: It should be noted that some punishments may turn into reinforcers- like a punishment spanking that actually encourages a repeat of the behavior.