Generally, it happens. The most common subject that will be discussed by everybody is politics. So whatever topic raised the discussion will just turn to that side. If a member is having a strong affiliation to some party he will try to use that occasion to bring the faults of the other party. Then it will go in a different direction. We should discuss the subject based on the merits and demerits of the subject proposed in the thread. But people will bring in the parties and that will become a big issue. Not only here, but many other places also I have seen this trend. Bringing in politics and discussing that in a rough way is not correct. The issue-based discussion will be always advisable. Even political discussions are also OK as long as one is in the limits and not using abusive language, I think.