... According to the seminary, the sharia prohibits use of such dyes that leave a layer on the hair as it obstructs water from reaching the roots of hair during wazu (ablution) and make it invalid.
... According to the Islamic seminary, sharia does not permit one to colour his or her hair black. Some believers had sought the view of the authorities of the seminary on this issue. Answering the questions, the seminary said colouring hair black was not in accordance with the shariah, though one could apply a colour like henna (mehndi) on the hair.
No Perfume Containing Alcohol: ...
It can really mess up your Namaz.
... To another question on the use of perfume, the seminary's reply on its website says," Namaz (prayers) are not valid if someone is having a tattoo or has sprayed a perfume with alcohol in it."