Is it true that even quality knives with wood handles can warp and be contaminated with bacteria? I was at Bed Bath &amp; Beyond and I spoke to one of the employees about knives with wood handles. She said that wood handles are no good because they warped from water and heat and were difficult to sanitize (especially if you're . But what about knives such as the Wusthof Ikon knives with blackwood? I find it hard to believe such an expensive knife could have those flaws, especially if one is properly cleaning, drying, and storing them properly. (My question isn't speficially about the Wusthoff knife, but about knives with wooden handles in general).
Knives are very hard-worked tools in the kitchen, and need to be easy to clean and maintain.

At all quality levels, unless resin impregnated or otherwise treated, wood does not stand up well to harsh treatment, such as frequent trips through the dishwasher.  Even if washed by hand, you want to wash it and then dry it, so the water doesn't soak in and lead over time to cracking and warping, plus a rough, unpleasant feel in the hand as the fibers expand and separate.

As to sanitation, wooden handles are much akin to cutting boards.  If treated properly, it is not an issue.  You can even, occassionaly, use a mild bleach solution (followed by rinsing and drying) to sanitize them.

If treated with reasonable care, by handwashing and immediate drying, wooden handles will perform very well, and of course they are very attractive.

Still, on balance, wooden handles require more care than some of the resin, plastic, or metal handles.  Choosing among the options is about balancing the feel and beauty and maintenance to your needs and desires.  For me, personally, I choose the resin handles as they are very durable and low maintenance.