Technically you can, since they do not absorb flavor. However, our Minhag (tradition) is to have separate dishes for dairy and meat. So, you should keep two sets of dishes to normally maintain separate for each, but if you’re serving a meat dinner, for example, and you run out of meat dishes, you can certainly use dairy dishes for that situation, since they do not absorb.
Benny Levy 
Howard Birenbaum 
Joyce Dworsky-Srour
Technically you can, since they do not absorb flavor. However, our Minhag (tradition) is to have separate dishes for dairy and meat. So, you should keep two sets of dishes to normally maintain separate for each, but if you’re serving a meat dinner, for example, and you run out of meat dishes, you can certainly use dairy dishes for that situation, since they do not absorb.