In reply to jess:
I haven't been to Carnmore for about 5 years, so my perspective may be totally out of date. However I haven't heard anything to the contrary that suggests it is wrong.
Carnmore is basically a barn. A dirt floor and a gaps at the sides too that allow the wind and - in the summer months - the midges in too.
It is/was watertight (if you sleep in the centre) and does provide a shelter of sorts. But it's a step below a usual bothy experience and more akin to a large doss.
I've slept there twice so, of course, the fact I went back does indicate it isn't THAT bad. But it's certainly not great, and the fact I returned was more to do with the paucity of shelter in a wonderfully remote location.