I think you are missing @a1fox3 point....Really your response seems that it needs more logic...
If you say that no one should hate Max because that's the way DS made him to be and didn't give us more options then what about Eric?, he made him a douchebag just so the player would find it easy in their hearts to kick him out, if he truly loved your mother and didn't want to fuck your family, being a good person would you want to kick him out?.
Both characters are nothing but complete scum...
And if that is an issue for someone perhaps their angst should be towards the person who made them both that way. Instead of trying to pick on and say he is better because he is less of a dbag.
As for the difference between Eric and Max, Max does love his family...Eric is a con artist and doesn't love anyone in that family just wants to fuck them while he cons them out of their house. He wouldn't even tell them his real name.
Max maybe a perv but the other is a crook. And it would seem you think wanting incest is more evil than being a crook.
I would disagree.
The entire game was mostly creep sex with very little love and no romance to be found.
DS has said many times he found it hard to put romance or love into these relationships.