Is the job done?
I mean, wether the person looks like working or not should not be relevant. Performance should be relevant. If that worker makes more stuff than others, where is the problem?
This person works another way than the average. Is probably not able to stay focused as much as its colleagues. Is able to make the job anyways. Well, then it's time to use that person the way it works. Not all workers are similar. Some need a lot of sweat to get things done. Others need a lot of pause time to get things done.
That being said, there i one situation in which those people can be a problem : it's when jealousy arises, and the whole team spirit falls down. It does not happen often, to my experience, but it may happen. In this case, strict measures shall be taken. But in other cases, why do you want to get rid of someone more productive than his colleagues?