When visiting any foreign you have to take precautions against parasites, and traveling to Guatemala is no different. However there are some parasites that no amount of medication can guard against; the human variety. They can be found at all the popular tourist attractions, speak English, as well as German, Italian and French, and are quite friendly. It is important to remember that no matter how harmless they seem their goal is to suck the money right out of your wallet.
These human parasites are easily identifiable; they wear an official looking laminated ID badge around their neck, and are always quick to ask if you need assistance or offer some helpful advice. Make sure you steer clear of these types of guides.