Ummmm Corker himself didn't run all that negative of a campaign. I mean, it's not like he showed up at the other guy's rally or said that the other guy would kick his dog.
The Republican National Comittee ran the add everyone cried about. Corker denounced it himself as soon as it came out.
Corker isn't an angel, but it was no more nasty than other races, including Ford's.