I'd say about 95% of the tweets I receive annoy me. Anything automated (I just did X at Y.com), location information (I don't give a fuck where you are right now), requests for RT, unnecessary high volume from a specific user...

Basically, unless you're tweeting something hilarious, an incredibly important piece of information about your life, or something you think your followers could be interested in (good article, certain photos, etc.) then I'm annoyed. I wouldn't even follow myself, given the opportunity.