Everybody is talking about using social media as a marketing tool, but what are the disadvantages of social media marketing?

I don't know why talking only a bout disadvantages , marketing  depends on using key tools to identify products such as: elements of promotion like :advertising and there are many elements in this field, public relations, publishing, 

There is also a social role that could be played through marketing 

full agree with mr.shahid answer....thank you mr shahid for this usefully answer 

Every Opportunity to evolve also comes with certain risks or disadvantages . Some of them could be:-

you will need to commit resources to managing your social media presence, responding to feedback and producing new content

it can be difficult to quantify the return on investment and the value of one channel over another

ineffective use - for example, using the network to push for sales without engaging with customers, or failing to respond to negative feedback - may damage your reputation

:-)

Creating more stress in life, taking away the healthy life style.

Connecting people with no thoughts( e.g. sending E-card to some one on birthday feel like its just just saying hello without any thought).

Lack of face to face interaction

Lot of jargon is being communicated in no time ( wasting time).

More interactivity puts more responsibility any thing goes wrong ll be more visible and viral. single customer negative feedback can damage whole reputation. 

Thanks to all valuable answers  

Most of the dangers of utilising social media comes from not understanding what a channel is good for. When communication teams utilise the various channels, be it traditional media or the not-so-new media, they have to understand the unique properties of each medium. This is something that communication teams and even media planners are still coming to grips with.

The danger comes when you try to replicate a communication meant for print and push it out to social verbatim. The danger comes when personnel who are not fully briefed on a specific product or service tries to answer a query. The danger comes when you talk like a business and not like a personification of that business. 

When it comes to social media, you have to develop your brand voice first before you even do your first posting. If your brand is a person what would he be like? What car would he or she drive? What would your brand do for fun? You see, you are talking directly to an individual and you have to be representation of an individual too. Humanise the organisation or brand. And most importantly, you have to train the people with access to your social accounts. 

From past experience and from what I have seen in the industry, most negative comments are generated from postings by employees who are not well trained or are frustrated and this seeps into their work. There are a lot of classic case studies out there. Using a social media management app can mitigate this in some ways, but humans will always be humans.

Using social media has its own advantages such as,  social media sites are free to access, create a profile and post information. The advantage of reaching your targeted market for little or no cash investment is substantial, and the audience wanting your information voluntarily joins or follows you. Pay-per-click advertisements on sites such as Facebook are "geo-targeted" according to specific criteria, to reach the correct audience. The viral nature of social media means that each person who reads your posts has the capability to spread the news farther within his own network, so information can reach a large number of people in a short time.

Yet there are some loopholes.

Updating your social media accounts takes time and effort. A senior person with knowledge about the company and products should handle your social media presence, and the cost in time means the media is not completely free. It is ongoing work to find new angles about your products continually and to post and re-post information. The information is only visible for a short time before newer posts replace it. In addition, publishing obvious advertising copy is unacceptable in the social media world, therefore you must present the information in the form of conversation or you will lose followers.

In my opinion,

social media is a very important marketing tool where the advantages are excellent, even disadvantages on social media turns into marketing.

As long as your firm's name is discussed on social media you're on the right track.                                                                                                                                                                                 Thank You.

the disadvantages is that sometimes social media exaggerate things, it would be nice if its on a good exaggeration but it would be worse if it includes negative feedback. And in that everyone follows on the trend.

It is all depends you. If you do it right then the social media is of your advantage but if you do it wrong it works against you. Just like any other marketing media. Responses are fairly quick here. Monitor it and act on the necessary steps.