I'm currently putting together a CD cover, and haven't been working that much with printing, so CMYK tends to confuse me a bit.
I'm going to place a logo inside a frame in InDesign. I added the exact same background color to the logo in Photoshop, as the background color of my InDesign document. Still the background in InDesign is slightly darker when I export the PDF as I look at it on screen (if I look at it from different angles).
Any ideas? I use the following black for both: C: 75% M: 68% Y: 67% K: 90%
You can also see that when I'm watching two version of my PDF (with transparent PSD placed in InDesign), it gets a white line around the cut area if I zoom it in or out. If I look at it in 'actual size', it looks normal.
Instead of going to the trouble of adding a rich black to the logo, make it transparent where it should be black and save in a transparency-supporting file format eg. PSD.
Instead of relying in the InDesign preview, output to PDF and open the Output Preview window (Tools > Print Production > ...). There you will be able to eye dropper the exact CMYK value of any point in your art. It's the definitive way to know what you're outputting.
That CMYK code for black is known as True black and is not that black on screen, but different appearances could be caused by the different colour profiles in PS or ID, and of course .pdf export settings, even though you used CMYK.
Also, about looking different from different angles.... Is your monitor properly calibrated? Does your monitor have that wide View angle? etc. Don`t worry if that black is not that dark on your screen, on paper it would be.