Fixing a broken hairdryer, keeping batteries from running down, things like that. If anyone finds a way to capture a few of these creatures and force them to help out in an evil lab, we'd love it if you could share your techniques. Again, these are three different looking species that share a common regard for humanity. They don't like us, and want to cause as much trouble for us as possible. Goblins and Bogeys both have the ability to become invisible, while Trolls can quickly sink into the ground or water and thus become functionally undetectable.
Bogeys are the smallest of the three, ranging anywhere from a few inches to nearly two feet.
They like to live inside houses, often in cupboards, attics, etc. We haven't heard of any lab infestations but imagine they could find plenty of places in a modern evil science lab to tuck away in as well. They are more annoying than anything else, hiding things, causing food to spoil, that sort of thing. We imagine they could ruin an awful lot of experiments. Goblins are a little larger, usually one to three feet, but sometimes much larger or smaller.