I don’t know anyone who says they “like” crawlspaces.  Unless your house is very new, some of the denizens of the darker places have found your crawlspace and made it home, for at least a while.  Our crew jokes about finding ‘freeze-dried’ rodents, but the fact is a crawlspace is a dirty and usually moist place here in the NW.

That dirty and moist part is the key: those two things are all that’s needed to attract the wrong sorts of guests.  Damp-wood termites, wood boring beetles, rats and mice, slugs, spiders, etc all appreciate a dark, moist crawlspace where there is organic matter to set up home in and hunt for cave-loving species.  This is why home inspectors hired by a buyer or seller will nearly always have something to say in the crawl space section of their reports.  Unless your home is new, there is likely some organic matter (dirt, sawdust, wood chunks, cardboard, etc) laying around down there.  Unless your house has a well-functioning foundation drainage system, you will have moisture trapped inside the foundation in the crawlspace.  If you have a leak in your plumbing (either an event or an ongoing leak), you will have moisture.

So check your crawlspace once in a while.  Or have someone who specializes in them check it out for you.  This isn’t supposed to be one of the fun things about owning a home, by the way.