The Blog de Edimedios – Inteligencia Colectiva [es] reflects on Twitter users who retweet without any previous selection.
[...] sometimes we got sick of “RETWEETitis” and for half an hour, we start retweeting everything that bumps into us. Each tweet we consider important, related to our tasks, etc etc.
About hashtags, the website notes:
Some people, for every word they write, put ahead the “hash” or “number asterik” which unconsciously -or on purpose- complicates reading the text itself. Another kind of Twitter users are those who don't use hashtags at all [...]. Very interesting content gets lost among the thousands and thousands of chips in the net… due to both kind of abuses -and unabuses?- of the hashTag.
[...] We should keep a healthy balance between using hashtags and retweeting, which aren't bad, but their continuous use may result in “silencing a Twitter user” or, worst case scenario, a “wild unfollow”.
It's possible to find the reasonable manner. We only have to look for it.