Well I met Batman and Robin...masquerading as the bug man and his son. Anyway it turns out I have very polite bats. The only guano they found was in a tray immediately below my attic air vent.
We didn't see any bats, but there was evidence (guano) that they were there. Much to my chagrin, I agreed to let them use sticky traps. If the bats are in my walls, (and I did hear scratching last night) there is just no way to get them out. They will either go into the basement and into the house - YIKES! or the sticky traps will get them in the attic. I really do feel sick about killing them, but they carry rabies and I just can't take a chance with them in the house.