Do you pursue negative marketing to kill your competition?

Well very difficult question , but as Senior manager , I am involved in different aspect of management and what prevails for me is company values rather than focusing on the competitors actions, but I can answer the question from another perspective and not from marketing aspect.
As decision maker I will search to turn the game in the market always in the benefit of my company, s.t like what Apple has done to move the market for keyboards and mp3 from monopoly to duopoly.
Without acting unethically i will search to steer the market and impose the company game.
We can be successful and acting ethically and comply to the right values our company is committed to as corporate social responsible.

In a very simplistic and straightforward manner the answer is a big emphatic NO! You can never pursue negative anything against your competition.
It may help you win a little battle, but you are on the way to lose a BIG war.
When you talk down your competition, people notice.
Sooner or later it will get you.
People who resort to negative campaign against the competition, have to hide something negative about their product/service/company.
Position yourself in the market as, "One to Beat".

It depends that what is negative marketing in your eyes? Like if Coke has used Pepsi in its ad as a negative marketing, its ethical & allowed.
But if you describe the weaknesses of a product by comparison with your product then its unethical.
So nothing is negative but its use is negative like using gun for military is positive but for killing people, its negative.

simply we should pursue the negative marketing campaign to avoid mistakes in our campaigns, but let the competitors' negative points to the sales team they can use it against their competitors in the market

In highly competitive categories like Cold Drinks, soaps etc company do adopt ambush marketing tactics.

The very basics of any product is to offer a unique value proposition which is the unique selling point (USP) of the product which if chosen carefully will implicitly differentiate your product from your competitors.
For example, "We are faster" which implicitly shows that the others are slower, "We are cheaper" which indicates that the others are more expensive.
If your value proposition doesn't behave like that then your product is a kind of "me too" products which raises immediately a red flag about your value creation process and indicates that immediate revision is needed to survive this product !!!!!!!!!!!! On the other hand, having your marketing plan revolving around showing the flaws of your competitors explicitly can be provocative to a lot of people as it will make them ask, why are those guys focusing that much on the flaws of their competitors rather than convincing us with the value they offer except if they really have nothing to say about themselves? !!!!!!!! I hope my answer was helpful :)

I am completely against negative marketing to tackle competition.
I think one should focus their resources and energies towards the betterment of one's own brand rather than trying to tarnish another brand.
Such tactics are always short lived and can result in major setbacks for yourself and hamper/destroy all the hard work and good will one has created in the past.
Such campaigns will only aggravate the situation and make your competition compete harder.
Also, more importantly, the information and broadcast laws of certain countries do not permit the use of negative marketing.
For eg.
the famous Pepsi Vs Coke ads(where each brand explicitly belittles the other one) are not permitted in countries like India.
So such campaigns cannot have a global appeal.
Hope this answers your question.

Negative marketing approach is "unethical".
Besides it can hamper the company's image within the industry in the long run.
A good marketing approach should focus on the positive sides, this way, good public relation/publicity is maintained.
Consumers are smart enough to be fooled.

What is negative marketing? If you emphasize good aspects of your business versus bad aspects of your competitors, there is nothing negative in that...

Companies rivalry intensity increase when the market is highly competitive with high buyer power but attempting to use this way of marketing in showing your competitor product weaknesses will only be bringing free marketing publicity to your competitor and people will preciser it as being envious of your competitor and will be faced with retaliation from your competition.
basically it will be just like shooting your self in the foot!