Facebook says the following in their help post about ticker and privacy:
Who can see stories about my comments and likes in ticker?
To control stories about your commenting activity in ticker and news feed, always check who can see the privacy of the posts you're commenting on. Learn more about sharing privacy. If you aren't comfortable with who can see the post, please don't comment on it or like it. If you do, a story about your activity will be eligible to appear on Facebook, including on your timeline (profile), in news feed and in ticker.
Remember, your comments and likes are only visible to people who can see the original post. For example, you might comment on a photo one of your family members posts just to family. A friend of yours who cannot already view the photo will not see a story in ticker about your comment.
Please note that unsubscribing from a friend's 'comments and likes' in your news feed, does not have any impact on whether your friends see it when you comment on or like their posts.
Also see this: http://www.wonderhowto.com/how-to-control-what-your-friends-see-about-you-their-facebook-tickers-0130113/