It really depends on the wood used. Some should absolutely, under no circumstance, be expose to a hot + wet environment. Some, you can put in the dishwasher and they are fine. I do use a lot of wooden cooking utensil and most of them go in the dishwasher. But I do have some nicer wooden spoon that are made from a more precious wood that I would always wash by hand.

Another thing is that a loot of wooden utensil are made in several piece stick together with glue. A lot of cutting board are made that way for example (especially the cheap ones). Most glue are not very dishwasher safe. It might be fine for a few wash, and then you end up with pieces of a cutting board.