Re polls in general, I'm not telling you they're necessarily all wrong, just that the ones in OH on statewide candidacies and statewide issues have been total jokes.
For background on just how bad they were in November, go here:
Worse Than Worthless: Ohio Polls
http://www.bizzyblog.com/?p=804
Whether that translates to polls about Bush's popularity being wrong is something I can't say for sure, but I wouldn't doubt it.
The Columbus Dispatch poll has an outstanding track record in statewide candidacies. The last time I researched the numbers (a year or two ago), they were the single most accurate polling organization in the country.
As you've indicated, their polling for last year's statewide reform measures were disastrously wrong, and there was a lot of discussion among the polling pundits about why a normally reliable polling outfit was off by such huge margins. Without getting into all of the specifics, the bottom line is that there are some major differences between polling for candidates and polling for issues, that make the latter much less reliable.
Given their overall track record, I would still put great stock in candidate polling from the Dispatch.