
Solution....
Pay a one time joining fee of $2 or something very small to "join twitter". This will cut down on spam and it's not enough to stop people from wanting to be apart of Twitter. Have a free use account that anyone can sign up for and tweet with, but your information isn't able to trend and hash information doesn't work unless you are a "Verified Tweeter" or pay the something small initial use and getting used to the full functionality of Twitter. This would cut down on bad topics but wouldn't stop people from adding newbies as friends or allowing them to view this information but just not allowing them to contribute to the searchable information.
It's also known that Twitter is working on a system in beta to Verify Accounts but the information from that isn't available to the public how this is rolling out and if it's only going to be for people who are of a more famous variety, like Tony LaRussa (Story 1 and Story 2)

I'm a broke guy and who lives in a college town, but I know that people who like Twitter and hate this gaming the system and spamming would love to get this stuff under control and wouldn't have a problem paying a one time, very small fee to "Verify" their account.