I don't really hate the genre. The main issue for me is plethora of harem are getting adapted every year and most of them are not even trying to stand out. Most are just fine with themselves being generic and mediocre. Not only they have subpar plots but they also have very generic and bland characters. If those weren't enough reasons to get turned off on the genre they will add horrible music which doesn't bring anything new to the table. I agree that there are good harem shows though. Even still, I think I would rather read a visual novel than watch a harem anime.