@VKAllen
Hmm. Not much. I assume, they hunt and kill whatever monster the village or town is having problems with?
Ah, it is as I expected.
Witchers undertake contracts from whomever posted the contract and conduct investigations. When they conduct such investigation, they rely heavily upon the information given from the contractor, and also physical tracks that may be left behind by the monster. This means, it would require Yuna to use her Witcher senses when looking for tracks and examining sites where the monster had been around or attacked. Even sometimes contractors could be wrong in their judgments. A werewolf that claimed to have stolen or attacked his chickens might as well be a petty but cunning thief. If Yuna had undertaken a contract with Ferghus, it would be very vlear to him that she is able to see through the illusory bandages that is wrapped around her eyes. Not only that, he would attenpt to move into close proximity of her in order to investigate whether it is indeed an illusion or if she's literally blind. This is because Witcher medallions react to magic-- given how you said that it was an illusory spell, the Medallion would react.