Firstly, unlike the Dean scream and Muskie's bawling, the Wright affair is guilt by association. Secondly, the way Obama has handled it has been marginally different from Dean and Muskie, and the speech has pulled large parts of the mainstream media back behind him.
Muskie's alledged crying happend during a press conference in which he was trying to defend himself and his wife from various vile smears put about in part (though this wasn't known at the time) by CREEP. By no sane standard (whether he cried or not) was anything that happend to Muskie even slightly his own fault.
Seeing as Muskie was basically destroyed by the media, this is obviously true.
If Muskie was such a sh**tty candidate, why did Nixon go to such lengths to eliminate him?