I'm reporting this issue and its respective workaround (thanks to research in cups as well as ubuntu support pages) so that it becomes easier for other linux mint users with the same or similar problem.
Linux Mint version: 15 (Olivia) - using any desktop (MATE / Cinnamon or xfce4) including all updates available so far.
Printer: Lexmark E230 connected via USB cable.
(it is reported by 'lsusb' as: ID 043d:009a Lexmark International, Inc.)
Printing driver (cups): pxlmono (It doesn't matter if it was installed by the system-config-printer tool or if it was installed by using the standard cups web interface, e.g. http://localhost:631 )
Computer Make/Model: Toshiba Satellite L645D - S4056
DESCRIPTION OF THE PROBLEM: The first print job (after turning on the computer and connecting the usb cable) comes out OK from the printer. After one or more successful print jobs the printer starts to output many sheets of paper with some "garbage" printed in one or two top lines only (actually some kind of postscript code I believe) instead of the text / image of the original document.
POSSIBLE EXPLANATION: For some reason the usb connection (cups usb backend) is reattached by the OS and the printer is somehow affected by this (it doesn't properly print later jobs).
WORKAROUND: Using administrator privileges (e.g. using "sudo" or "su") run:
lpadmin -p PRINTER_NAME -o usb-no-reattach-default=true
(replace PRINTER_NAME with the actual printer name (find this out with the command 'lpstat -p' )
One can confirm the "usb-no-reattach" option has been enabled by inspecting the file /etc/cups/printers.conf
If printers.conf it wasn't properly updated running the same command (' lpadmin -p PRINTER_NAME -o usb-no-reattach-default=true') a second time may work.
Now turn the printer off for a while (may disconnect usb cable too to make sure) and then turn it on again and reconnect the cable.
Try printing again.
OUTCOME (after using the fix): Now it prints perfectly.
The issue is somehow documented in the source code of cups usb backend where a few printers have this workaround already built in, including another lexmark device. This one seems to require this "quirk" too...
Additional sources of information for those facing the same or similar printing problems under Linux:
And after downloading and extracting cups 1.6.3 source code tarball from http://www.cups.org look for "usb-no-reattach" in the following source file:
(excelent troubleshooting guide including additional troubleshooting steps as well as workarounds for many kinds of printing problems with Ubuntu and possibly also Linux Mint).