Hey flomman, OK let us try taking this from the top. My background first, I have operated my own print shop since 1998 and I do 75% of the design work that I print. I produce over 100 printed products every month spot color --> full color --> Spot UV & foiling, etc... you get the picture. First, if your monitor is not color calibrated, color calibration is almost impossible to achieve in the finished printed product. Second, if your printer does not ask for or require a color profile then 90% of the time they toss it out in preflight (my experience, others may have different points of view). Third, one reason you only need a color profile if your printer does not require it, is if you are trying to calibrate to multiple printers/presses say if your company is printing its brochure in different shops in multiple locales and you would like them to be as close to exact as possible. I use profiles: fogra 39, 51 and 52 (if I am remembering correctly), and GRACoL2006.
Question? Are you printing your calendar on a web press? If not then you are definitely using the wrong profile due to the max ink coverage for web coated SWOP is 300% whereas the other sheetfed profiles range to 340-350%, this could account for the lighter color with less ink density being used for that profile when converted. It is just a guess though... if I think of something else I will post it, but I have printed hundreds of files without color profiling i.e. MS Office files converted to PDF... and have not had many problems, there were a few but I would say 95%+ printed fine without a hitch. I hope this might help you.
The pdf web/screen prints fine due to it being RGB color space, which is a wider color gamut and 99% of said desktop printers understand RGB conversion very well for desktop printing. So if that is the case, it is the color profile messing things up. What happens when you create a pdf with color profiles turned off?
Off topic: Adobe products do not share color profiles between them unless set up in Adobe Bridge (not sure if this is still true in version Creative Suite CC as I have not upgraded yet) FYI... In my ID settings I do not save the profile but keep the CMYK values as my option.
Regards,
mnawij