I don’t think the issue is whether state officials are more corrupt. It’s just that in giving them power to appoint Senators, voters are foregoing an opportunity to serve as a counterweight to state-level corruption. With direct election, there’s at least the prospect that every so often (e.g., 2010), voters will get angry enough to “throw the rascals out.” But if Senators are directly elected, voters can’t exercise that power except very indirectly. They can “throw the rascals out” at the state level, but since 1/3 of Senators are re-elected (or re-appointed if the Amendment 17 is repealed), it would take a lot of time for that to play out in terms of improving the quality of Senators appointed. In the meantime, there’s ample opportunity for the newly elected state legislators to become corrupted by the time they get around to deciding whether Senator X should stay or go.
I have mixed feelings about Amendment 17 repeal, so I’m not arguing strongly against the possibility. I’m just explaining the logic of those who oppose it.
Can't they already do that in House elections?