Best way of building blogs for backlinks?

I plan on registering 1-15 gmail accounts, creating 4-5 free blog accounts with each (blogger, wordpress, livejournal) for a total of ~50 blogs. Then create 5-6 1000 word articles for every keyword/page and spin them really well, spin words, pages and paragraphs so each article is only 300-400 words but very unique. Post articles on all blogs with backlinks with keywords in anchor.

I have a couple of questions to this:
Can I mix articles with different subjects on the same blog and have good results? As in is it ok to put articles about both babies and about cars on the blog for best results or should I keep the blogs separate and create a new set for every niche?

How often do I need to update them to make them stay up and not get deleted as spam blogs?

What would be a good way to monetize these? I dont want to risk my adsense account but does google allow other ads on their hosted blogs? I create them mainly for backlinks but maybe they would earn some on sheer volume.

Thanks for any answers and sorry for the noobishness

Edit: These blogs will link back to adsense minisites not to eachother.

 

This looks like a lot of work! Have you ever done it before, does it work?

 

I think it'll be better if you create just 5-10 blogs tops and build links to those, so when you link to your site from one of the spun articles on those blogs, the link will have more weight.

 

a lot of topic which dont have even any similar words. car-seo-etc. is not good for SEO. but it is better making a high quality blog 10 with niche than making plenty of useless blogs.

 

Yeah this sounds like a better idea I guess, less work anyway.

 

This sounds like a great idea! Might get a little crazy in the middle, but I'd love to see the results

 

bad bad bad...google doesn't like this stuff. Be careful. Hard work is a nice way to reach the goal. But not always, and this is surely not the way to work hard, I am afraid. Make few blogs and then make each and every effort that the content is unique. Because google respects unique content and elevates sites containing them, with respect to PR as well as SERp.

 

I have read about this in some autoblog books before. Certainly, google allows you to run ad other than adsense on blogger platform. I would suggest you to keep your contents in specific niche as it may help you to get targeted traffic plus you might make some money from targeted advertisers as well. Good luck to you!

 

If a website has a backlink profile full of only blogspot/wordpress etc - this is not good.

you need proper domains also. eg domain.com