Have to say I've never had any major problems leasebreaking, but lease ending is usually problematic. First time I did it because I'd bought a house, my rental had just been sold and the new owner wanted to gut the bathroom (bathroom was fine but blue. Kitchen was 60s and barely useable. I could have lived with no kitchen and a rent increase but not no bathroom) and didn't seem to think I'd have a problem living there with a toddler, no bathroom, and then a $50pw rent jump. He was wrong, I left, he got really nitpicky and I lost half the bond to trivial things. Couldn't be bothered fighting anything, as it was I lost a day's rent out of the bond for coming back and cleaning extra the morning after I was supposed to be out and STILL lost more bond for missing a few crumbs here and there. Amazing how a couple of crumbs in the bottom of an ancient decrepid worn out oven can cost $150 in cleaning fees. I'd never even used the oven ... if I knew he was going to be such a pedantic idiot I would have stopped paying rent and left asap when the house changed owners, the previous owner was quite nice, and I'd turned the yard from a weed-infested mess into something nice while I was there, which was lost on the new owner as he'd never seen it in the old state. At least I didn't get charged advertising or anything as he wanted to renovate.
Second time I was only leaving a few weeks before the end of the lease, the owner took the opportunity to sell the unit instead of reletting it, the PM was really slack (never fixed the running hot water tap, managed to inspect the wrong unit instead of mine a couple times, and when I initially got the keys the old tenant and most of her stuff were still in the unit) and with such a bad taste in my mouth after last time I just stopped paying rent 4 weeks before I was due to leave. The PM took about 4 months to lodge the paperwork for the bond. He was probably too excited about the fat juicy commission for selling the place that he forgot it was once a rental.
Really does put into perspective that if you're not nice to tenants, they are very likely to go vindictive on you. And its usually the managed properties that are bad, private landlords seem to be quite ok with most things as long as you talk to them and they are a lot more flexible. PMs seem to do anything within their power to not communicate, ignore your requests, not do work like fix running hot taps that cost you (not them) hundreds in electricity, and always have secretaries to screen calls so you have to leave 500 messages before they deign to phone you back months later.