Its improbable for a common man to speculate the truthfulness of the vairagya of a renunciate.However, it makes sense to err on the side of caution, by not dishonouring the sage who has chosen the path .
Pujyasri Chandrashekara Saraswati Swami says, it is only when one does not seek pleasure, and practices self-denial that the light of Atmic Knowledge will shrine in him.
Hindu Dharma The Universal Way of Life
In his Bhashya on Gita, 4.11 Sri Shankara says that it is impossible for a person to be a seeker of liberation and also a seeker of the fruits of action at the same time. This means that Vividisha(renunciation of a seeker) can be said to be there only when there is total detachment towards everything else)
Detachment is of three kinds-- weak, strong and stronger. The detachment that arises on the occurrence of some calamity, is not lasting and is categorized as weak. Such a temporary feeling of detachment is of no use and does not make a person eligible for Sannyasa. The determination not to marry, beget children and live the life of a householder is categorized as 'strong' detachment.
There are four varieties of Vividisha Sannyasa(renunciation of a seeker). These are-- Kutichaka, Bahoodaka, Hamsa and Paramahamsa. The detachment described as 'strong' makes the person eligible only for the varieties of Sannyasa called Kutichaka and Bahoodaka. Both of them are 'Tridandins' i.e. they carry three long thin sticks knotted together, emblematic of the triple renunciation of everything connected with body, mind and speech. The Kutichaka resides in a secluded hermitage. The Bahoodaka keeps moving from one holy place to another. The choice as to which of these two varieties a person with the kind of detachment described as 'strong' should take depends on whether he is physically fit to move about from place to place or not.
Stronger' detachment entitles the person to take the Hamsa and Paramahamsa
The Paramahamsa who is a Vidvat Sannyasin (renunciation of the knower)is described as one who is like a new-born baby, whose mind is free from the effects of the pairs of opposites, devoid of all possessions, who is firmly established in the path to Brahman, whose mind is free from desires, who, just to maintain life without being under obligation to any one, goes about begging at the prescribed time, using his belly as the begging bowl, and is unperturbed whether he gets it or not, without a fixed dwelling, lives in places such as a derelict house, a temple, a hay-stack, under a tree, in a pottery, in a house where sacrificial fire is kept, on the riverside, in a mountain cave, in the hollow of a tree, or a place for the performance of sacrifices built near a spring. He is free from all striving, devoid of the feeling of "I and mine", ever meditates on the pure Self, is established in the supreme Self, gives up all actions and ultimately gives up his body with total detachment.
Sri SN Sastri (Summary of Jivanmuktiviveka of Swami Vidyaranya)
Sri Shankara also classifies mumukshutvam(desire for liberation) into Ati-Mandha,Mandha,Madhyama and Teevra.
(Disregarding all pseudo sanyaasis with malacious intent), concerning only sampradhaya sanyaasis ,it should be understood that,though they are of varying competencies,they may still safeguard and propogate vedic(vedantic)/sampradhaya knowledge, dharma, and live a life with a value of 'sarva bhootha hitham'. Shaastra of Sanyaasa ashrama, as prequisite , itself cannot be forfeited,for in some cases it is alledged that it is not practiced in letter and spirit.
Qualities of the Guru
The Guru should be well-versed in the scriptures, sinless, free from desires. The mind of the Guru is always fixed on Brahman. He is full of compassion. He is always intent on helping others without the expectation of anything in return. The disciple should approach the Guru with humility and pray to him to instruct him on the means to attain liberation.
(Vivekachudamani commentary by Swami Chandrashekara Bharathi ,translation Sri SN Sastri)
There is an indispensable requirement of sampradhaya Gurus , for the sustanence of traditional systems of sampradhaya s and Veda dharma samrakshana ,lest the tradition may perish.