CNN has a poll out showing (of course) Clinton leading trump by 13 points. In this poll they discuss the unfavorable numbers of both which are similar and within the MOE.
Then they mention past races and say this, “Bill Clintons FAVORABLES were 42% in 1992”. Notice how rather than report on his UNFAVORABLES as being 58% (higher than Trumps are now) they spin it by reporting the lower number (favorable) and compare it to the higher number of the opponents UNfavorables.
When Trump calls the media “dishonest” he has it dead right.
A 42% favorable rating does not translate to or imply a 58% unfavorable rating. The two numbers won't add up to 100% due to "no opinion/don't know". For example, in May, 1992, when Clinton's favorable rating was 42%, his unfavorable was 48% -- not 58%.