We never had anything bad happen that related to demons that I know of.
I did however; buy a bureau one time from a thrift shop. The drawers were rather hard to open, after dealing with that for a few months, one day I asked my JW husband if there was anything he could do to fix them.
We took all the drawers out and noticed, stuck in behind the top right was a couple of papers. One was a drawing of Satan, and on it was printed "I'm a little Devil", the other had a brief poem about a devil, both looked like something from a child's coloring book.
We both thought it odd, given the circumstances, instead of freaking out we just laughed about it and threw them away.
Nothing ever came of it.
For instance, a high percentage of people experience sleep paralysis, where they wake but are unable to move.
I experienced this once and that was "Enough" for me !! I didn't think of demons, or feel that was the cause... but it was one of the most terrifying experiences I'd ever had. I was literaly screaming in my head for my husband to wake up, of course, I was unable to make a sound or move. It lasted about a minute, but felt like forever. Awful !!
I did some research on it and learned what it was, and that if a person just remains calm it will stop quicker, hard to do though.