How to remove a general layer of black 'ink'?

[esac]

This whole photograph seems to have a layer of ink on top of it (I am guessing the background should be white, and his cheek shadow seems too dark).

Any idea how to remove this from the whole picture in general?

[mistermonday]

Esac, there are many ways to address the problem which could include extracting the gentleman from the background and/or some dodge and burn layers, etc.
One quick method for (shown below) is to grab the actual Dodge tool for the PS toolbar, in the options bar select Midtones, and paint over those areas to remove the grunge. Each time you paint over the grunge it will get whiter.
You can do the same for the face.
Regards, Murray

[esac]

Thanks. I tried that, and spent some time trying to make it perfect, here is what I came up with, primarily using the dodge tool, and adjusting levels.

[mistermonday]

That looks much better than the original.
Regards, Murray

[robmac]

You could also try rather than the doge toll on the pixel layer making a dodge curve
with a black mask as you will have much more control and it's less destructive.
What you have done looks better than before but maybe you could soften the transitions a bit more.