Quoting from the chapter "Mimangsa beliefs" of the book Hindu Dharma:
The sannyasin deprives himself of karma ('karma- bhrashta'). To look at him is sinful and you must atone for it. To look at the sinner, to talk to him, to dine with him, " say Mandanamisra and mimamsakas like, "is to earn sin. To look at a sanyasin is equally sinful. "
Even many of vaishnavas avoid looking at sanyasins who have shaved their heads and abandoned the sacred thread.
I want to know the references from the mimamsa texts or any other scriptures that talk of the above mentioned points?