Whether trading volume increased noticeably before or after the news was released is the simplest way to judge.
Take this news item: Sky’s TVL fell 15% in a week, and the circulating supply of USDS dropped to $5.59 billion; $BTC was down 0.29% intraday.
The impact of bearish news often hits quickly and fades just as fast. The key is to watch for any further bad news.