Like @cantsay said the topic has been raised before by lots of members myself included. The answer most gave were they are bots or nuked account's but this answer
The Brand New phenomenon is down to the Evil IP system. When an account is banned the IP address assigned some evil points and all IP addresses close to it a smaller number of evil points. When a new account is signed up from an IP address that has a certain number of evil points they are required to pay a fee before they can post (the higher the evil score the higher the fee). The spambots sign up many accounts to find one they can post from for free.
by TheQuin is one I find interesting and close to the truth.
Because all their accounts are have been opened around the same time. I will investigate the alt of these accounts. If they are involved in any illegal activity I will find out and take strict action against them.
Do help us with these oh Sherlock Holmes.