Dante doesn't like the vacuum either. If it comes too close in his direction, he backs off, but he's still curious enough to have to know where it is so he's following it around. Other than that, he's not really a dog that gets scared easily. If it's stormy and dark outside he can be a little spooked by shadows and sometimes out in the forest there are some random areas he'll get scared of and refuse to walk over. I've never noticed anything but he's probably sensing something I can't, so we just walk around it.