Had the same experience on one of the 767's from PRG last year. My headrest was dangling by one thread at a 45 degree angle. The seat pocket was torn all down one side and flapping loose.
Not exactly my proudest moment, as I was travelling with some colleagues from the US and had been crowing about BA shorthaul service compared to US domestics. Particularly galling as I'd been on a nice new(ish) A320 on the way out.
In my opinion the 757's should be dumped ASAP and replaced by the excellent A321 (I think they have 10 on order at the moment) and the 767's should be smartened up. BA were going to sell them to the RAF as tankers until, whoops, the MoD got p*ssed with BAE and went with the Airbus (ironically as BAE owns 20% of it, nothing like having a finger in both pies).
Anyway they'll orobably be kept until the 7e7 becomes available in 2008 (by which time they'll need replacing anyway).
Just me tuppence worth.
PhilH