They were always corrupt, even when they were running contraband cotton through the lines in 1863 and 1864 to sell for the accounts of (among others) Lincoln political general Ben Butler (later Governor of Massachusetts).
After the war, we got the Credit Mobilier, Orville Babcock's Whiskey Ring, the phony "personhood [and rights]" of artificial persons (corporations), and other juridical and political bagatelles too numerous to mention, right up to Albert Fall's Teapot Dome follies, when he sold oil out of the Navy Petroleum Reserve for graft money.
That was back when Washington grafters were still thinking small.
Now they graft and loot on an intercontinental scale, and as you say, they're able to keep it out of the papers, and the People in the dark.
Now it get nastier
Canadidate Cotton’s campaign manager is funding anti-Sasse pacs to the tune of several 100k. The latest one is a hit pieces using Sasse’s children in commercial so bizzaro it’s bound to more confuse.
Just like 2012 in Deb Fischer’s campaign, the GOPe is throwing everything with the hopes that something stinks.