He once shushed the crowd and once didn't shake Almagro's hand. Because of those 2 incidents in his 10+ years long tennis career he is now officially a bad person and is presumed to spend his free time abusing kittens.
Sure, not like every match he plays is done so with a foul attitude and followed up by his incredibly rude press conferences. A bad reputation doesn't come from one or two incidents, it's earned.