I have a bog standard Sennheiser pair -MM50i I think.
I've managed to exchange them as faulty when they broke, the packaging clearly says 'guaranteed for two years' - which is standard on EU bought electronic items.
Bought them from an Apple store so had the receipt on an email, got them exchanged straight away.
On my third pair now, it wasn't a hassle at all. I could probably argue 'reasonable wear and tear' but didn't need to.