Why create a fake account?

We decided to look into why fake profiles follow who they do and why are they created in the first place. Our initial thoughts were, it could be somebody being nosey and wanting to look at your tweets but didn't want to follow you on their actual account. Another reason people create fake accounts is they like to create a different online identity as it makes them feel good using a different photo etc. However this would be on a small scale. 

Larger scale

Software to generate thousands of Twitter accounts is widely available. These programs send data to Twitter through proxy IP addresses, generate names and user names without the user going through Twitter at all (some will even scrape the information and pictures from random accounts and replicate profiles with a couple of random misspellings).