I’m not sure. I think there was a time they were not like they are now.
Before it was the FBI it was the Bureau of Investigation. Hoover took over and formed the FBI in his own image; a crooked organization that spied on anyone and everyone. Hoover never let the truth get in the way of what HE wanted and he wasn’t above blackmail to get it. He instituted illegal break ins for himself (FBI) and Presidents.
Administrations came and went. Hoover remained until he died.
He NEVER let anything tarnish the image of the FBI. That is why there are better memories of it. Modern directors aren’t as careful as Hoover was.
In 1941 the English sent one of their European spies to warn Washington that the Japanese were planning to attack Pearl Harbor. For some reason the agent was sent to Hoover. JEH laughed the man out of the office, had him followed and started a smear campaign against the agent in the halls of power. We know what happened on December 7, 1941.