"We have had several pest control people out. They say nothing in the attic, basement, garage. But why do I hear scratching, click-like noises, and thumps?"

Maybe the pest control guys are wrong?

Just because they didn't find anything doesn't mean anything. I've had problems like that before, especially in the winter months. Sounds to me like rats, mice, or squirrels.

I say probably mice. Put out some sticky traps with a dab of peanut. Also check the outside for any holes that squirrels could enter. Red squirrels will chew their own holes.

Might be ghosts and spirits. Instead of calling pest control,call a shaman next time. Most places require this activity be revealed when selling a house.

In this post she is less a spammer than you. Makes one wonder.