It's really a question of frequency and format. A lot of tweeters who aren't advertising come off as equally annoying and spammy because of their excessive tweeting/retweeting. I heard that the half life of a tweet is about 18 seconds. I can't attest to the accuracy of that, but if it were true, think of how many times one ad must be tweeted. Good thing it's so easy to unfollow.

Hulu is now doing that. Your real name appears with your comment.