The ruling concerning begging

My question is: For those people who come to the mosque and ask for money and Sadaqa and for those either male or female who stay outside the mosque or asking in the streets near the traffic signals asking people to give them money or Sadaqa, Is it okay to give them money and I treat it like Sadaqa although I feel not confident when I give them because I don not trust them whether they are poor or not or whether they really need it. Should I give them and Allah will treat it as Sadaqa or should I give the money for the official agency like Fatwa Center and Jalyiat Center where they can distribute it them selfish on the poor people. Please help me answering this question.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Allah, The Great and Almighty, urges Muslims to give Sadaqa and promises them good reward Here and Hereafter.
He Says (interpretation of meaning): {And those in whose wealth there is a known right, For the beggar who asks, and for the unlucky who has lost his property and wealth, (and his means of living has been straitened);} [70: 24-25].
He also dispraises misery and misers: {And let not those who covetously withhold of that which Allâh has bestowed on them of His Bounty (Wealth) think that it is good for them (and so they do not pay the obligatory Zakât). Nay, it will be worse for them; …} [3: 180].
Basing on the above-statements, a Muslim is advised to give those who seek for help and donation, especially if we do not know their true financial situation or we are sure that they are in need.
Suppose that one gives Sadaqa to another one who is not in need, we state that the giver will be rewarded and he is not required to be sure of the others' dire need, while the receiver will be sinful. It is sufficient to depend on one's appearance that may indicate need.
Thus, we are not required to seek for one's secret financial state, but we give Sadaqa according to our evaluation of the situation of the one whom we give the Sadaqa. Then, if our Sadaqa reaches one whom we do not we want, our Sadaqa - Insha Allah - will be accepted and valid.
Our above-opinion is based on the Prophetic Hadith: "A man said to himself: 'Tonight I will give something in Sadaqa, so he went out with his Sadaqa and (unknowingly) gave it to a thief. The next morning he was told by the people that he had given Sadaqa to a thief. (On hearing this), he said: 'O Allah! Praised be You. Certainly I will give Sadaqa again'. So, he went out with his Sadaqa and (unknowingly) gave it to an adulteress. The next morning he was told that he had given Sadaqa to an adulteress. The man said: 'O Allah! Praised be You. (I gave my Sadaqa to an adulteress. Certainly I will give Sadaqa again'. Thus he went out with his Sadaqa and again and (unknowingly) gave it to a rich man. The next morning the people said, the night before he had given his Sadaqa to a wealthy man. He said: 'O Allah! Praised be You (I have given my Sadaqa) to an adulteress, a thief and a rich person …it was said to him: your Sadaqa was accepted" [Reported by Imams al-Bukhari and Muslim ].
However, if we are sure that someone is not poor - according to our evaluation and his appearance and other signs - we should not give him.
At last, we believe that it is necessary to specify amounts of Sadaqa money to the reliable societies that have faithful means by which they recognize the poor and needy and give them through the best and most polite means.
Allah knows best.