Yes, those accounts ARE fake. No doubt about it. And they keep tweeting and re-tweeting each other because part of the requirements on buying Twitter followers is that you want ACTIVE Twitter accounts. Accounts that are doing something on Twitter. So these Twitter bot accounts are fake AND they tweet fake garbage so that the Twitter automation software people run doesn't flag the account as fake or inactive. Thus you have a legitimate fake bot account you can use in your network if you're selling followers.
It doesn't make it ok, but it's the state of things online. Everyone wants followers. They want Facebook fans. They want likes, +1's, and re-tweets, and Web site traffic. All of which can be bought, and quite easily too.