Welcome! If they are stabilized, you will have an easier time with them, especially being new to pen turning. Any spalted wood will likely be a little punky here and there (soft spots). That being said, I've turned quite a few that were not stabilized. They will suck up some thin CA pretty quickly, which will stabilize them. Just stop and apply a little here and there as you turn (with the lathe off, of course). Sharp tools are a must if you don't... well, they are pretty much a must for anything if you want clean results.