My mum's cat used to regularly barf, even though we checked him out and he was fine...in fact, it earned him the affectionate nick name of the boffer and he progressed from heaving by his bowl to leaving artistically placed chunks of regurgitated Whiskas on the stairs...
Fast forward to my mum's next two cats - and they do the same..and seem to favour the soft landing for it..ie the shag pile
I took pity on neighbours cat the other day, let him in, fed him...he wanders into living room with a guilty expression and hey presto...he had barfed up stairs..
Why?!!!