Not just auto spam; a lot of sites haunted the trends board and wrote stories. The most hilarious example was when 4chan bulked searched for "justin bieber syphillis" and created a burst of stories across the web.
That's unfortunate. It was a really useful tool. The Hot Topics are not particularly useful, well, unless you want to know what People Magazine is going to print in their next issue.
The new Google Trends UI is still useful for hot topics (Hey, Oracle just won the America's Cup!), but less useful for spammers.