Hashtags on Twitter: Spam, or genuinely useful?

The first Twitter hashtag was born on August 23, 2007 by Chris Messina, the first tweet with a hashtag read as follows: “how do you feel about using # (pound) for groups. As in #barcamp [msg]?” In today's world, hashtags make tweets more meaningful and identifiable. No conference or speech is complete without a hashtag these days.This week I was at a conference about social media and fittingly there was an official hashtag: #smj2, so I followed the hashtag intently throughout the day to see what everyone's thoughts were about the conference. Suddenly, a few hours into the conference people who weren't at the conference started to get annoyed with the use of this particular tag. The angry tweets ranged from "Can people stop spamming me with #smj2" and "If people tweet #smj2 again I will unfollow you", just to name a few.Now this got me thinking, if I was seeing this on my Twitter stream, how would I feel about it? First I might see if this event is relevant to me, and if so I'd create a search around that hashtag so I could follow the event more closely. If not, then I'd use what I think is the most underrated Twitter feature: lists, which would enable me to filter out the noise from my main stream. So I totally understand the annoyance around hashtag clutter, but one could argue that there are tools Twitter have in place for users to filter out the noise.So are hashtags here to stay? Undoubtedly so. Hashtags, when used correctly, can be of tremendous value, but when they're not it can be easily classed as spam. So what are the solutions?

• Identify whether or not the hashtag is relevant to you
• If the noise is getting too crowded then divert to your Twitter lists to reduce the noise

What are your tips for filtering out hashtag clutter/spam?