I have heard multiple times that "one should never cut raw meat on a wooden cutting board nor mix it using a wooden spoon."
The reason most often cited is that apparently bacteria can survive in the wood's pores.
I also found this PDF from the University of Wisconsin–Madison where it is written:
Using. Avoid cutting raw meat or poultry directly on a butcher block or wooden cutting board. Instead, place a plastic cutting board on the wooden surface and use the plastic board as the cutting surface. This will protect the wood and prevent it from becoming contaminated.
Is there any truth in this claim?