Stopped seeing ads on Twitter? Probably not. Because while the social network has been experimenting with showing less promotional content, it's only for its most valuable of users. Re/code reports that "to a small group of some of its most prominent and active users... Twitter is an ad-free, or nearly ad-free, experience". The idea, it seems, is to try and keep a hold of these very important tweeters by bombarding them with a little less junk. Presumably it's calculated that these key influencers, for want of a better term, are more important to the social network than the revenue they can generate by showing them ads.
According to "sources" at Twitter, the exclusive status is chosen based on a bunch of criteria, including volume and reach of the tweets, as well as, presumably, how famous you are. Good luck achieving those giddy heights of Twitter success.