Tarrtufe is several things, but the best description of Tarrtufe is as a parasite. Parasites draw nutrients from their host in order to survive. Much like Tarrtufe, parasites also deceive their host, some are capable of fooling their host's immune system into believing the parasite is a part of their body. And much like a tick or a leach, even once the host is aware, removing the parasite can be painful.
Tarttufe is much like a parasite in many ways, by taking advantage of others and deceiving them. He uses his deceitfulness to steal from them without their knowledge hidden behind the veil of a holly man. Mimicking a person of trustworthiness.