Most of the time this is merely ignorance on their part. Therefore, if you see someone wiping the Yemeni Corner or the Black Stone with his left hand, point out to him that such an act is not an expression of reverence. One does not honor the Sacred House by wiping the Yemeni Corner or the Black Stone with the left hand; rather, wipe them with the right.
The same rule applies when leaving the lavatory. After you have entered the restroom to relieve yourself of urine or feces and then come out, step out with the right foot first, for the area outside the lavatory is more deserving of honor than the lavatory itself. Hence, when you exit, begin with the right foot.
The principle also governs giving and receiving and similar matters. If you want to hand something to your companion, hand it over with the right hand; and if you wish to take something from him, take it with the right hand. These are the manners of Islam.
Yet some people give with the left hand and take with the left, imagining that this is “progress,” because the unbelieving West receives and gives with the left. Glorified be Allah! The people of the Left will be given the left, for the unbelievers are the People of the Left, whereas the believers are the People of the Right. That is why you will always find the unbeliever preferring the left: he belongs to the left side.