Was that the case here? If so then that's easy enough that on the balance of probabilities you can say he said it
Yes, in the Kamara case that is what happened.
To quote [MENTION=30352]McTavish[/MENTION] link to the article, Jonathan Liew, rightly asks the question of why someone would put themselves through the process of calling out a racist, being highlighted and questioned in the media, not getting a single thing mixed up etc. etc. only to be doing it for a big old joke and a laugh.
Bong should've been believed, Kamara should be believed, (unfortunately) the next footballer who falls victim to a racist comment should be believed. That's how you eradicate it.