The DirectXTex library expands legacy 24bpp files automatically since there is no DXGI equivalent format. The existing code, however, converts them as if they were RGB data, when in fact they are BGR.
 
This can be verified by looking at the color masks:
 
bitCount 24
R: 00ff0000 G: 0000ff00 B: 000000ff A: 00000000
 
Attached is an repro image. If you load it with DirectXTex, the result looks 'bluetoned' instead of normal.