Biiiiiig metal head here, but you may be surprised (or not, as the case may be) to find I like everything.
NOW HOLD YOUR HORSES, BILLY.
There's a few exceptions. While I enjoy, for instance, rap music from a musical and talent perspective, I can't bring myself to respect or enjoy rappers that drag on and on about how many hoes they have in the crib , and simultaneously claiming to be from the ghetto, and have real roots, but still rap about the golden toilet paper they buy and throw away every day.
That was a bit of a run-on, but understandable, I think.
I don't particularly enjoy screamo and the like, but I don't loathe it. Same could got for some overly produced pop.
I'd like to address a few points though:
Defending Autotune. This may seem blasphemous in a way, but I don't mind autotune being used. Two caveats, though. One is that if you use autotune, and are idolised as a great singer, then you can go fuck yourself. The other is that autotune used well is impossible to spot. Likewise, the popular use of it means that some perfect singers will be bashed for using it when they don't. It's a lose-lose battle. So I say don't hate on the autotune, yo.
As for screaming/growling, and the use thereof to "cover up the fact they can't sing", I'm gonna disagree. Okay, let's say you are of the camp that says "Oh, anyone can scream/growl!", and you encounter a metalhead who enjoys the aforementioned techniques. If you say that, I will ask you to demonstrate, since you know so goddamn much. At which point, assuming you complied, a horrible noise akin to a broken Pokémon cry will assault my ears, and you will probably hurt your throat, cough, and talk funny all day. I will then laugh at you, and possibly call you names. This is because you are likely bad at it, and you are likely bad at it because you haven't practised. Y'know, liek wot reel singarz du!
I'm a musician, myself, and I spent a few years learning how to growl. I say learning, I did it over and over again until I achieved a sound I wanted, and could do it with relative ease with a bit of concentration and (best of all) didn't hurt. Bam. Just leik wot reeeal singarz du!
I can sing as well. I can hit notes and all that good stuff, but the core tone of my voice (something not easily changed in a hurry) is kinda... eh. If I need to sing clean on anything, I do a bit of tone tweaking to beef it up a little.
Screaming, on the other hand, is something I can't do. I don't have a great falsetto anyway, and my upper range is not very high. I can more or less get the more scream-y sound, but it hurts to do, and I can't sustain it. It's hard. Difficult. Like what real singing is.
I guess what I am trying to say is don't knock what you don't know. I sure as hell can't play a viola, but that doesn't mean I go around saying "OMG YOU ARE ONLY PLAYING THAT BECAUSE THE CELLO WAS TO BIG 4 U AND U SUK LOL LOLOLOL", because even though I know little about playing a viola (or indeed, a cello) I can still appreciate that skill is required.
Much of the above applies to extreme metal of most kinds (progressive, death, black etc etc etc). If you bash it as "just noise" or even worse "just random notes" I will be very cross. To a lot of people, progressive jazz is "just random notes and chords" but that shit is very complicated.
Incidentally, jazz players tend to make very good metal guitarists, and vice versa.
Apologies for the MASSIVE rant that was only tangentially related to the topic.