Thats because you're so hetero it hurts
Obviously quite a few people are turned on by it else it wouldn't exist. The 'black on blonde' specifically black on 'cheating wife/gf' subgenre seems to largely centre on possible guilt/cuckold feelings white american men have towards black american men (presumably because of racial stereotyping); it isn't that difficult to go from that to 'omg 3 men' etc. In britain we seem to prefer our wimmin cheating on us with other wimmin (there isn't as big an interracial taboo).
There doesn't seem to be an absolute limit on the degeneracy of men; which doesn't bode well for the future. Personally i find a certain thrill with pornstars who don't 'look' like they should be in porn getting degraded, and then obviously despising them for going to that level. Once they can take it all up the arse and grunt without caring im not interested
Theres probably a niche for 'psychological porn' similar to meatholes type interviews - where the actual depravity is less important (or non existent) than making the girls cry at the thought of their mothers/fathers/siblings watching them. To paraphrase Woody Allen, sex isn't right unless its dirty, and if they don't feel dirty it isn't porn.