I have seen sites doing a lot of spam and their search results have topped for their keywords. Now my question is that they have been lasting for now over a month. How much time will they last more? Secondly, building links with some content related to my site at plenty of other sites manually along with adding unique fresh content & keeping the site updated will that be a nice SEO.
Lasting over a month isn't a long time. Believe me, it's chore having to put the work in to constantly SPAM your site then have Google tear it down. It isn't a sustainable business model by any means. Unless you like to make short term money, have it dry up rinse and repeat constantly through the year fighting Google. Nobody can give an accurate time frame to which their site will be buried in the SERPS. Google is constantly tweaking their algorithm. I know I'm going to sound like everybody else but it is true by all means. Make quality content that engages your readers while also networking with people in your niche. If you build it the traffic will come! Think long term monetization and don't be short sighted.
A month is not that long. SPAM is never a good thing, and it will never stand that long especially with all the Google updates.
Don't be surprised when a site that was built with spam crumbles to the ground. Google's algorithms and link detection is getting better and better everyday. It's not the way to build a website these days.
I will assure you that the sites doing with the spamming this soon going to be slapped down by the Google, i will say no one... just no one is going to stand in front of the Google Algorithm i think you have heard the news about expedia slapped down by the Google Algorithm. Yes building links with unique and fresh content will definitely going to help you out as it is like by the Google and users to....
Ok... if i have make a new blog to my main site... & i keep on adding articles (fresh & unique) daily to it related to pages of my main site & at the end of articles on that blog post add a link to the main site page... Now will that link help my main site page in any terms...
Why don't you try to make you blog in you're domain only ..... like if your site is "xyz.com" then create blog on the same i.e. "xyz.com/blogabc" and try to put all you're unique work/fresh work over there as in this way you would be more visible to the search engine and you don't need to add link there, you have the authority to add link there but be sure not to do too much of it...... and i guess this would be helpful for you in terms of SEO too.... !!