The Baal HaTurim [Bamidbar 6:6] says that the reason a Nazir cannot be near a dead body is so that if his Nezirus brings him Ruach HaKodesh, people should not suspect that it is not Ruach HaKodesh, but that he is really communicating with evil spirits through the dead (Doresh El HaMeisim). Rav Elyashiv, zt"l, in Divrei Aggada, points out that although a Navi has Ruach HaKodesh, he has no restriction to avoid dead bodies.
What is the difference? He answers, that the pasuk by Nazir says (6:2), “Ish Ki Yafli Lindor.” The Ibn Ezra says that the word Yafli is from the word Peleh, a wonder. The whole world follows their desires, and this person chooses not to do so. This is a wonder!
By a Navi everyone sees and knows that he is holy person, and they know his Ruach HaKodesh is attained through spiritual purity. However, when they see a simple person, whose whole greatness is that he merely refrains from the physical pleasure of drinking wine for thirty days, they cannot fathom the holiness of this act; and the last thing they think is that this act can raise him to the level of Ruach HaKodesh. They suspect that he has been doing some forbidden black magic through the dead. Therefore, the Torah tells the Nazir to stay away from dead bodies to avoid suspicion. [Till here from Rav Elyashiv, zt"l]
The upshot is that an average person can achieve unbelievable high levels of kedusha by refraining from physical pleasures - certainly from powerfully enticing ones and certainly from ones that are assur!