If MLK was lecturing on family values and the importance of marriage - and was having an affair - that would be hypocritical.
But if he was only campaigning for civil rights, I could care less what he does in his marriage.
It's only when leaders tell people how to live - then break tehse very same rules - that they suck. Regular joes, schmore, and heroes who wish to bang people they're not married to - I could care less. Their business.