"Greys would be so hard to keep clean! So glad I own a black and not a grey!" In response to this, I ride a large grey pony and he is constantly dirty. Grey horses do get cancer though. My pony had surgery for it.
Camargue Stallions Play-Fighting in Water by John Hallam The stallions were brought to the pond, for them to interact. There was a big age difference, so they were not very active. Any apparent action was play-fighting and not serious aggression