If the only possible way you can catch a bigoted manager is by hoping that he spent a lot of time hurling racial abuse at Black people under his own name, then I think you really need to work on your management processes.

sure, I find out about it a year later, since i am a small company, and now 3 black people were not hired because of it. Is this a big win? also, I do believe that the word abuse is being devalued, and that such simple insults do not really qualify as abuse in general, lets not forget that a great deal of black people love to use the same words when talking to eachother, black celebrities get famous singing the word, self describing as such.

That is a very white understanding of what abuse means.

Also, it seems wild to me that you think a small company means you somehow have less ability to supervise your employees. What's your plan if you hire a racist who wasn't dumb enough to post openly? Just let him go to it?