I think I know why I like B&W even better. If I post a color jpg "Saved For Web" from Photoshop with the recommend sRGB profile, on one site it will look right on and on another it will look like Velvia ca 1985.
What are you doing? Two sets of images, one desaturated for Flickr and Facebook and the destructive photo sites?
It's really harsh on flesh tones, looks like people got spray tans.