In the description of the known description:
"… in addition you can act as an action Look through the eyes of your friend and hear what he hears until the beginning of your next round, to take advantage of the special senses of the familiar. During this time, you are deaf and blind to your own senses. "
They use the senses of their confidant (eyes and ears). When the familiar scouts, use the creature's ability / ability bonuses. Even if you have experience in perception, this -1-wisdom rating lizard will be a terrible scout.
For this reason, many roles choose different shapes for their confidants. Is it jet black? Then summon a bat with 60ft blindsight. Dense fog? Maybe you'll turn into an owl with perception check bonuses.