Well, the core of the printing system is 'cups', so that's a good place to put printing bugs unless you have something more specific.
Also see: https://wiki.ubuntu.com/DebuggingPrintingProblems
However, there are always at least 3 parts to a printing problem;
1) The application that produces the file/stream to be printed
2) The drivers for the particular printer
3) The central print queuing stuff
If you can figure out which one of these is the cause of your problem then it makes debugging easier, and you might also be able to find a more specific package.
However they can interact (the famous bug where printing from OpenOffice to brother printers on a tuesday is probably the worst case!).
So try and split the problem down:
a) If you get the application to print to a postscript or PDF files (try both if you have the option) and then look at the resulting postscript or PDF file in a viewer is it right? If it is then you're bug is less likely to be printer specific or even cups.
b) Does only that app have a problem?
c) Does the problem go away if you use some other options on the printer (e.g. don't use n-up printing or double sided)
If you can't print at all then lsusb to see if the printer is seen at all (if USB) is a good bet, as are the CUPS logs.