Others feel itchy when they touch themselves is mostly caused by nerve reflexes.
The surface of human skin is full of peripheral nerves, can feel the stimulation inside and outside the body, and transformed into nerve impulses, transmitted to the center. Other people touch themselves belongs to an external stimulus, the peripheral nerves of the epidermis will feel itchy after perception, generally normal physiological phenomenon.
And part of the population peripheral nerve sensitivity is higher, will be more likely to feel itchy. But there is also a part of the peripheral nerves are not sensitive, or for the itch sensory threshold is higher, there may be other people touch their skin and do not feel itchy situation.
Other people may feel itchy when they touch their own skin for other reasons, but if there is no discomfort associated with the symptoms, it is usually normal. If you experience itchiness or pimples, it is recommended that you seek medical attention.