last week i felt a spider crawling on my head inside my motorcycle helmet, since i was already on the road just told myself i was imagining things, i wished that was the case
If you ever had a bedbugs infection, you are traumatized for life. Any movement immediately triggers you and you can't relax until you looked everywhere and found no bedbugs.
It is actually useful for detecting bugs crawling on your skin. Having them bump into hairs is way more effective than just giving them a free, smooth pass. Sure, we get lots of false positives, but in an evolutionary context where bug bites, venom, and diseases are significantly more dangerous, 100 false positives are worth avoiding the 1 false negative.