It goes without saying that snorers are the greatest curse to afflict humankind. Their rasping, hooting, roaring, shuddering (I've heard all kinds) sounds are carefully calibrated to cause maximum irritation to the light sleepers they afflict. They should all be consigned to the 7th circle of Hell immediately, alongside the Taleban, the Khmer Rouge, and that referee who gave England a last minute penalty at Murrayfield in 1994. They [goes on and on in this vein for several minutes, you probably don't need to read it]
But so far I've been pretty lucky. I've shared hostel dorms with up to 12 people and can only recall one really bad night. That was at the end of the Milford Track. Ironically sharing huts with at least 7 people on the Track itself was no trouble, but sharing with 3 in the Milford Backpackers lodge was torture - a Japanese man and a very large lady (I was concerned about the strength of the bed - she was in the bunk above me), joined together in unharmonious symphony and proved impervious to all the pokes, kicks, sirens and rabid possums I threw at them.
It probably helps that nearly all dorms seem to be mixed these days; the girls snore in a ladylike fashion if at all, and perhaps the guys subconsciously tone it down in order to avoid making a bad impression (this may not be good science). Most dorms were single sex when I did Europe by train in 1992, and the snoring was far worse.
Snoring is no problem if you're so tired you're asleep as soon as your head hits the pillow. One way to achieve this is lots of beers, but the one I've just tried is 2 days cycling in heavy rain on Queen Charlotte Track (pictured with latest trusty steed). There's great views of the sounds on either side of this peninsula, and despite a few too many steep sections, the track is a nice mix of coastal and ridgetop. But I didn't have much time to look at the views, more focused on staying upright, it was very slippery at times. Only one fall, which given velocity and rocky landing caused surprisingly little damage, but really tiring, mentally as well as physically.
One other strange experience on the Track, a large good quality restaurant at Punga Cove (where I stayed) to myself! There were only a few occupants that night and everyone else was cooking for themselves. So waitress and chef had an evening solely devoted to making me happy, I could get used to it!