The Use of Race to De-legitimate Conservatives: Are Predominantly White Events and Institutions Per se Illegitimate?

I have often been uncomfortable with the way in which liberals and the media use race as a de-legitimating tool in disputes with conservatives.  Clive Crook nicely points this out here with respect to the recent Glenn Beck rally.

Are predominantly-white events and institutions per se illegitimate or does the criticism apply only to conservatives?  It strikes me that when liberals use race in this way, they are simply using race cynically and politically.

I am willing to explore the claim that predominantly white events and institutions are not representative of America and therefore have less claim to legitimacy.  But if this is a serious inquiry, it should not be directed selectively against conservatives.  Otherwise, the inquiry is betrayed by its cynical manner in which it is selectively deployed and it is the cause of racial equality that suffers.