To be honest, he left the england series early but with vetorri I think it was genuine (even though he was shown up by Ashley Giles of all people ). i guess I deep down assume some players could over do the "i'm injured thing"(alex tudor springs to mind despite playing the aussies) and some dont (freddie, thorpe, gough).
Not that the aussies are imune to it though see here
http://news.bbc.co.uk/sport1/hi/foot...ol/4330249.stm