fishing expedition 手段不当的调查；（为诬陷他人或搜集新闻材料而进行的）非法摸底调查

【例句】
The senator says the investigation is a fishing expedition by his enemies to see if they can find anything he has ever done that might hurt his political career.
那位参议员声称，这次调查是他政敌的蓄意盘查，目的是搜罗挖掘他是否有不端行为，以便损毁他的政治生涯。

When your car got broken into, those two officers were on a fishing expedition.
当您的车子被窃，这两个警察是在摸底。