I'm not following the reasoning in your comment. So because fishing expeditions are possible we shouldn't ever go after political opponents for actual crimes?
You can, for instance, make your same argument about Dick Cheney and his relations with Halliburton which were equally obviously corrupt. Yet lo and behold, plenty of showy investigations, and the political establishment finds that the political establishment did nothing wrong, well at least nothing deserving of anything worse than a few very gentle taps on the wrist.
Yes, other administrations were corrupt, going back at least to Andrew Jackson. No, from what I can tell, they weren't this corrupt (with the possible exception of Grant).
What crime did you want him found guilty of exactly?
There are other falsehoods in your comment as well.