I think that sharing is a good thing, but you do need to be careful how much you post on each site. For example, your Facebook friends won't appreciate it if you share 10 or 20 articles each day as it will clog up their newsfeeds. The same goes for Twitter or HubPages.
Share hubs that you think are good writing, useful and entertaining, but do so judiciously. Your followers are more likely to read what you share if you don't overwhelm them with posts.
In fact, if you clog up people's feeds, they are very likely to unsubscribe from your posts and you will lose the whole purpose of sharing.