Websites typically strive for relevant information that is timely and current. For whatever reason, a ghost site has not been maintained or updated by its owner. The problem is that ghost sites are hard to detect, because it can be difficult to determine exactly how frequently a site is maintained. Depending on the nature of the content, it may or may not matter. For example, a reference site with timeless content that isn't updated is less of an issue than a website that deals with more time-sensitive subject matter.