Mike Tyson pretended sometimes. Infact, in one fight, he went as far as to go down and out, losing the match and thereby providing himself with something to put on his CV to impress the bosses down at The Hangover.
Evander Holyfield, there are times where I suspect he's exaggerating how hurt he may be so that his opponents get lulled into a false sense of security only to miraculously come back and rally. I think its his way of using a psychological ploy so that when he is infact hurt you proceed with caution.
Do you not think he had proved his Philly image before this? To be fair though, a low blow can look very light but can hurt real bad. I give fighters the benefit of the doubt in these occasions.
Ricardo Mayorga used to wiggle his legs after taking full blown hooks from the likes of Trinidad and one-two's from the likes of Forrest
Your mentality has to change when you pass 40. Mother Nature and Father Time are both trying to get you to retire, so it requires some real skulduggery to hold them off.