The nasty streak argument is one put out to justify unpleasant players. Not necessary, plenty of world class players who don't have the character of a Keane or Ronaldo. Go through the ages, Pele, Beckanbauer, Muller, Platini, Pirlo, Lineker, Charlton, Moore, Iniesta, Xavi, Messi. They are just off the top of my head, a random bunch. Plenty more if I put my mind to it.
I'm not old enough to recall watching the others, but i've seen them 3 dive and hound refs plenty. That's equally against the spirit of the game. I think some players are media darlings and people choose not to see the "bad" things they do....
Messi for a start has been charged with tax fraud (as have many Barcelona darlings), so is it only on the pitch that we judge their morals or off it too?