So wood that naturally expands and contracts, creating squeaky floors. You don't even have to step on it if the temperature or humidity changes. My last house had gaps in the crawl space, so lots of shifting occurred.
Mice in the walls. It's always either mice or slightly moving plumbing pipes. I hate living near agricultural fields because mice love to try and move in every autumn.
Footsteps I'll chalk up to people hearing things. I don't know how many times I've thought I've heard footsteps but the moment I catch it, it disappears.
Low-reservoir flushing happened all the time with my last toilet. I know it had a leak but it was slow enough that I didn't much care until it started flushing once a week.
I'm not scared of my attic, I just don't like being up there because it's always hot, it smells weird, and there's too many exposed nails at face level. I imagine most people are only mildly "scared" of their basements or attics because they don't go in them very much, and fear of the unknown/unfamiliar is very real.
..... Maybe I am haunted...