Anonymous tips are often made for nefarious reasons. Sometimes it's revenge. Sometimes jealousy. On the other hand, sometimes it's some kind of mistake. When law enforcement acts on these tips they should carefully investigate before taking action, but unfortunately they often fail to do so. When it comes to illegal plants there have been many cases of mistaken identity. For instance, there are a number of plants which superficially resemble marijuana. If a neighbor looks over your fence and sees a look alike growing in your yard, he or she might not realize that it's not marijuana and may call the cops if they consider growing marijuana something worth reporting. (Otherwise, they might hop over the fence and grab the plant for themselves.) Upon receiving a report regarding illegal marijuana plants, law enforcement personnel might not be adequately trained to be able to tell the difference between a plant which looks like marijuana and the real thing.