It promised to be enthralling, a joint appearance of the philandering John Edwards and his cancer-stricken wife, Elizabeth, as part of the Salem State College Series. A mob of national media was expected to attend, eager to grill Edwards in a pre-speech press conference regarding his recent admission of marital infidelity. Until yesterday, when the couple canceled their Tuesday, Sept. 23, appearance. No reason for the cancellation was given, Salem State spokeswoman Karen Cady said. "They both canceled. We contracted for both of them, and they both canceled." Political consultant Michael Goldman of Marblehead, a supporter of Edwards, had planned...