Oh God, The Slap was AWFUL! Every character was entirely offensive, I hated it and felt really grubby and tainted afterwards. I read it on holiday and then had to cart it around because I couldn't bear to sully anyone else with it!
Gone Girl - also full of hateful characters and just very poor. Yuck.
And yet, unlikeable characters is not necessarily a loser for me - Suite Francaise has some really unpleasant and hateful people but they're compelling and you want to know what happens to them. Same with Dorothy Whipple, some of her characters are deeply unpleasant but gripping.
I read a thing called When the Dead Cry Out by Hilary Bonner for a book club. Man it was bad! It's a crime thriller, the central character was a tough female detective, but she was saddled with the trope of "tough cookie but all she wants is a maaaaaaaaaaaaaan" which was annoying. The dialogue was completely unbelievable, and the central crime was solved about 3/4 of the way through so then there was a lot of book left with nothing to fill it. Badly plotted, poorly drawn characters and badly written, it was completely woeful and I hated it!
I also hated The Kite Runner. He was so completely up himself, I found myself saying out loud "it's not all about you" a lot of times.
And The Bookseller of Kabul - poverty tourism at its worst. She bangs on about how poor they are and then takes a lot of their hospitality without giving anything in return. I know there is a big hospitality culture in a lot of parts of the world, but it really felt like she was abusing it to her own advantage. And there are ways of returning the hospitality in some way that are not insulting, but I didn't get any sense that she did that.