The skepticism is nothing new. It's not like this was not described or addressed in the Bible:
"Master, we saw another casting the devils out in Your name, and we forbade him, because he followed not with us" "Forbid him not, for there is no man who does a miracle in my name that can soon afterward speak evil of Me", And also: "Forbid him not, for he who is not against us is for us". In short, God has chosen his way of operation long ago. He will use everyone He can, and sort out the details later.
Jesus remarked, when questioned if His healing was from God:
"Satan cannot cast out satan, for his kingdom will not stand"
We should have this in mind. When someone gets healed, satan cannot be the one who healed them. What a terrible thing to suggest, that healing can come from satan, don't we know to make a difference between the Spirit's fruits and demonic fruits? Vehemently saying things like these is sure to invoke condemnation. These people think they know the Spirit but they don't, and when they finally die and meet Him for real whose presence so repulsed them on earth, what do you think happens?
Also Jesus said:
"When therefore ye who are evil know how to give good gifts to your children, how much more the Father in Heaven will give good things to those who ask Him?"
So we don't ask for a fish, and get a snake. We don't ask for bread, to get a stone. We don't sincerely pray to God to help us only to get a demonic "not of God" response, because it's not how this works, Jesus said it's not how it works, and people who still doubt need to re-read their Bibles. God always hears. Always helps. It's only that His help doesn't always come in the form and on time schedule we imagined. But sometimes it does, though!
But the OP didn't even specify anything about any church, or pastor, or their beliefs or legitimacy. They simply stated that poor people come to church and pray for healing for hours and they have many breakthroughs through faith and prayer. Why would our reflex be to doubt that, or believe that these desperate people come and ask for a fish and Father gives them a snake?