Terracotta dishware is food safe and can be washed in the dishwasher and used in the microwave. It can be placed in the refrigerator but should not be placed in the freezer. For oven use, place with food in a cold oven and then turn on the heat. When removing from the oven, place on a thick folded towel to avoid thermal shock. Sticky dried on food is easily washed off by filling with warm soapy water for a few minutes.
I usually do not glaze the bottoms of my pieces. Why? Because glazed bottoms must be stilted (held above the kiln shelf on metal pins) to keep them from fusing to the shelf during the firing process. This very often creates “stilt marks” or sharp little craters and/or volcanos that need to be sanded so the piece is safe to handle and doesn’t scratch table tops or fingers. Stilting a piece also doesn’t provide even support under a plate or bowl during firing which sometimes contributes to warping or sagging. So given my druthers, I avoid glazing the bottom.
Unglazed bottoms do tend to be more porous and will absorb moisture in the dishwasher or in a sink full of water. You can dry the plates more thoroughly by leaving them in a drain rack overnight to air dry after removing from the dishwasher or by hand washing and not soaking in the sink. This has not been much of an issue with my plates and cups even though they are constantly in and out of the dishwasher. Sometimes a plate remains unused in the cupboard under the rest of the dishes where it may develop a little mildew which gets washed off the bottom of the plate and the cupboard surface. I have also noticed moisture develop under a warm microwaved plate or a hot mug of coffee. I generally use place mats and coasters and this is a non issue for me.