The problem is always going to be with modern realistic or even impressionistic work that is subjective is it's necessarily marked resemblance to paintings of the past. My experience with these artists is that they too consciously copy styles, subject matter, colors and composition of old masters. The only artist so far that anyone has name that could be absolutely confirmed as a Republican is Thomas Kinkade. 'Nuff said in that case. Yes, I would figure that a western art museum in Texas could harbor some Bush fans!
Privately financed museums can certainly have an agenda, that's for sure. I think what the poster meant by great artists are those who should be known by anyone seriously interested in art and whose work is in major museums. Of course, there are those who are not happy about the quality of their work being judged as second rate or banal and not worthy of being shown in a museum. Hitler happens to be one of them.