Have you ever turned on and synchronized your Creative Suite Color Management?
Just as important, are you using a calibrated monitor? Preferably an IPS LCD panel? Did you calibrate with a colorimeter or spectrophotometer?
I'm using InDesign CS5 to create several ads that will be printed in black and white in my client's local newspaper. Each ad includes a grayscale photo. Per the newspaper's instructions, I've done all of my color correction in Photoshop and I'm using the PDF Preset they sent me, which outputs the color to a US Newspaper (NSAP 2007) profile.
That's probably not the right thing to do for a grayscale ad... It sounds like the ad is being converted from K only to a four-color mix.
For the very best results, in Photoshop, Edit > Color Settings... and press the More Options button if it's showing, then from the Gray dropdown choose Load Gray... and find the SNAP profile in the dialog that will open up. This will load the K channel from the CMYK profile as the gray profile.
In ID, assign the same SNAP profile to the document (Edit > Assign Profiles...), and whn you export the ad leave the colors unchanged.
Newsprint is a case where ID's different ways of handling grayscale become more obvious. Modern CMYK profiles can profile the black ink color, which would never be absolute black on press. Not only will a CMYK profile show 0|0|0|100 as a lighter value than absolute black, it might also show the black ink as having some "color". So when the 100% black ink patch is measured for the profile its "color" might not measure as neutral, which I think is the case with newsprint.
If you duplicate an ID doc and assign SNAP to one and the default SWOP to the other, and turn on Overprint/Sep Preview you will get a preview of the two black ink colors:
What further complicates things is, in Photoshop grayscale profiles don't return the more accurate black ink "color" preview. 100% grayscale blacks always preview as absolute black (0|0|0 RGB), which won't in fact happen on press and with newprint the effect will be more obvious.
Great suggestions. Thanks guys!