My problem with the planting is not that it makes Hillary dishonest. Nor is it that it's reminiscent of what the Bush administration has done. Her campaign's merely requested that people ask softball questions. One can't even compare that with what the Bush administration has done, and at taxpayer funded events, moreover.
The problem is that planting all of the questions insulates the candidates. This makes it much harder for them to think on their feet. This was made evidently clear by Senator Edwards' campaign video "The Politics of Parsing," made in response to Senator Clinton's non-answer on the question about driver's licenses for undocumented immigrants.
Three months ago, the three were thrown out of a taxpayer-funded Bush Social Security event in Denver by a person they thought was a Secret Service agent, because of a "No More Blood for Oil" bumper sticker on one of their cars. Similar incidents have occurred at other presidential events around the country, and the three have not been silent since.
But there will also inevitably be unscripted situations on the campaign trail, no matter how good a job campaign staff does. Consider Senator George Allen last year:
Or Senator Conrad Burns:
Or Senator Conrad Burns again:
I think if the two of them had been used to less-than-totally friendly audiences, they'd have been more prepared to think on their feet and not say and do things so incredibly damaging to their campaigns.