I have a Canon XL1s and have been using it as a VTR for capturing footage from 7 x 63 min Panasonic MQ tapes. I want to use my friends miniDV cam as a VTR to lessen future wear & tear on my XL1s.

Does anyone know if the lubricant problem or any other issues occur when you put your MiniDV tape in another camera that has dirty heads/mix of lubs/etc. to capture, then put the tape back in the pro camera.
Will lubricant transfer from bad camera to tape to good camera or any other issues that I could face?

Also, how often do you clean your cameras heads? (I have a panasonic minidv head cleaner, cleaned once so far, after recording about 5 hours of footage in smokey bars).

I can imagine that dirt and other things in the other camera can
stick to a tape and transfer to your other camera indeed.

Just don't use cleaner tape often. Use it when camera tells you to clean heads, if you experience rec/play dropouts or if you changing brands. Too much use of head cleaner can worn your heads quite quickly.