The recent arrest of the Democrat governor of Illinois gave me a thought, which might even be original:
There are powerful parallels between the Clintons and the Obamas and the effects that their rise to the presidency had on their erstwhile associates. In both cases, the men (and their wives) came from humble backgrounds; in both cases they saw (or, at any rate, used) politics as a means of making money. In both cases, they (and their wives) were deeply connected to various schemes of graft, sometimes shading into corruption, that enriched themselves and their close associates.
In both cases, their associates played important roles in their early political careers. Without knowing the details, I speculate that the associates rejoiced at the prospect of these men off to Washington: just think of the money that could be made there!
Except . . . it didn't turn out that way. In both cases, power brought visibility, and with visibility comes scrutiny. While the candidates themselves were unhindered, the associates not only saw no profit, but faced prison in the bargain.
The takeaway is this: both the national media and federal law enforcement have become adept at rooting out the kind of graft that otherwise goes unmolested at the local and state level. Those involved in such graft flourish only to the extent they can avoid the national spotlight. If their political front men (Clinton, Obama) go national, they themselves may escape the law, but they extend no cover: everyone else is in for some rough handling.
My other thought is this: is corruption really this universal? We're going two-for-two now for scandal-prone self-made politicians. (GWB doesn't count, obviously: he was already wealthy before he went into politics, and he didn't "come through the ranks".)