Actually, they are not. They are totally verified accounts of people genuinely receiving healing miracles. The girl who was bitten by a snake is named Therese. When she got bitten, her mother saw that she was not breathing, so she carried the girl to the nearest Christian missionary for prayer. It took her three hours to get to the missionary. The missionary prayed, and the girl started breathing and recovered with no brain damage. The girl went on to gain a masters degree. The author who related the story actually went to the African village and met Therese and her mother who told him exactly how it happened. This was not a lie, nor an exaggeration. By the way the author is not a Pentecostal. He attends a small Baptist church.
I think that you have been conditioned to believe that any account is exaggerated or a lie by some lunatic Pentecostal, even though the healings have been verified by medical professionals who had diagnosed the medical condition through tests and Xrays, and afterward testified that the condition had entirely disappeared through subsequent Xrays.
There is the account of a woman in a rest home confined to a wheelchair because of a definite medical condition, and who would constantly say, "I wish I could walk again". A young preacher visited, saw the lady in the wheelchair, heard what she said, and said, "In the Name of Jesus get out of that wheel chair and walk!" She immediately got up and walked, and was totally puzzled about how she could actually walk when before she couldn't. The medical condition definitely was not psychosomatic, but real. The others in the rest home were amazed at the miracle.
The problem is not that you can't believe these accounts to be true, but because of your conditioning against the modern manifestation of the gifts, you won't believe that they are genuine and real. I don't think that you would choose to believe if a miracle of healing occurred right before your eyes. You would have to find some reason to believe it was not a genuine healing even if it was verified by medical professionals.
Frankly, it doesn't matter much to me whether you believe that healing miracles happen today or not. That is your personal choice. But when you give teaching to others that healing miracles are not for today, then that is quite another matter, because someone who might have had the faith to believe God for a healing miracle might be robbed of the opportunity by believing your teaching, and remain sick, when the Lord might have healed him.
Miracles of healing are powerful signs that Jesus Christ is alive today, that God's nature is love and compassion. Anyone can say that Jesus Christ is loving and compassionate, but it is just words until the Holy Spirit demonstrates it by miracles of healing and release from demonic oppression.