Auto-Tweeting is where you either set up your Twitter account to automatically post every new item on your blog or where you preschedule tweets to go out at a certain time.
This sounds like it could save you a lot of time and improve your social media visability. However, if you are putting your Twitter account on auto-drive you are missing the point of Twitter.
Firstly by posting a link to every blog post you create, is coming awfully close to spamming. And whats more its breaking one the golden rules of social media - "don't talk about yourself!" Funnily enough, people don't want to be notified every time you create a new post in your Twitter stream. If you do want to promote your blog posts either tweet the odd one or create a separate Twitter account for your blog.
Next up its schedulling tweets to be posted at a later date. I don't get this! Twitter is all about the "now". People are talking about current events. So unless you are a mind reader, you are probably not talking about current events and instead using Twitter just to promote your own crap.
Twiiter ain't about promotion or marketing. Sure you can spread the word about your stuff on Twitter but limit it and only do it if it adds value to the conversation.
Remember the great thing about Twitter is you can be responsible for what you see. Don't be afraid to unfollow someone if all they are doing is promoting their own products 24/7.