Many businesses are creating hashtags on Twitter in order to promote their goods or services. These hashtags get repeated in Tweets in order to emphasize the business and create a brand identity in 140 characters.
It is a wonderful business strategy.
The business owner must treat those hashtags as trademarks.
Why? A trademark is an identifier of the quality of the goods or services and the source of those goods or services identified by the mark. In this case, the hashtag on Twitter performs the exact same purpose. This means that there is a risk of trademark infringement or dilution by the use of a hashtag that is not reviewed for possible confusion with other trademarks.
In fact, there are businesses that receive cease-and-desist letters because of hashtags that conflict with other trademarks. So, there is certainly a risk of having issues without doing due diligence and trademark searches on hashtags that are created to promote a business on Twitter.