People just don't seem to like them as a whole... especially the current top ones because of one reason or another yet each one is arguably the best at their weight class.

Byrdne of the most hated heavyweights out there.
Tarver: Good fighter IMO, and if he could keep his mouth shut would deserve to be almost as popular as he thinks he is.
Calzaghe: Just recently has gotten the respect he deserves, but his work has always been overshadowed.
Wright: Great skilled fighter who due to his style not skill has been shunned by alot of the more bloodthirsty boxing fans because he prefers to dominate an opponent than take chances and try to ko them.
Pacquiao: I never thought he got the respect he deserved for a long time, and I think alot of people underestimate him because of where he is from as opposed to what he has accomplished.
Calderon: Due to his weight catagory, and lack of power it seems he just doesn't get the publicity he deserves IMO.
Judah:Not the best in his division as PBF proved, but still extremely skilled and quick unfortunately his attitude and disrespect of others have left his status as infamous.

Call me crazy, but I think southpaws are taking over industry faster than the Brits.

Other guys in the recent past who deserve credit as southpaws
Pernell Whitaker: I think he didn't get the respect he deserved for his skill, but also he did drugs which didn't help anything.
Marvin Hagler: Easily as good as any of the other four greats in his time, but he was still overshadowed simply because he lost to Leonard, and he didn't have the media friendly character that the others possessed.
Michael Nunn: drugs or he would have been an ATG.
Reggie Johnson: He was very skilled, but he was in a time of very good middlewegihts and smw, but I think he could have stood in there with pretty anyone either than Roy Jones Jr. when he was at his best.

There are probably loads more, but its just a courious thing that I noticed.