I have heard that there were many witnesses to the miracles Wigglesworth did. That was quite a while back so a lot of them are probably dead by now. If you really wanted to research it, maybe you should find some witnesses.
That is the Biblical way for establishing facts of what happened, having witnesses that is.
You want to know why the miracles always happen overseas and not here. Well, I doubt you'd go to any African country where everyone has seen a miracle, but that doesn't mean some of them aren't happening. So sure, someone could go to where miracles happened and ask someone on the street who had never heard of it. Contrary to popular belief, if a miracle or healing occurs, not everyone hears about it and believes in it.
I heard that happened, btw, with a revival on Timur In Indonesia (I'm not sure if it was Indonesia or the part that went independant since). This Indonesian preacher wrote a book about all kinds of supernatural things happening as a group of villagers were filled with the Spirit and went around preaching the Gospel, water into wine (or was it tea into wine), walking on water (up to the knees, though) etc. I've heard some people went there and did not find evidence of the miracles. On the other hand, i met a man from there who had done his Bible school thesis on the miracles and interviewed a number of witnesses. I never did get a copy of that thesis before I moved, though he was willing to share it with me.
In the US, if someone gets healed, it may be explained as a wrong diagnosis or going into remission. I would imagine a lot of doctors don't want healings publicized for fear of ridicule, or at least wouldn't announce it, especially if they don't believe in healing.
Evander Hollyfield was diagnosed with a heart condition. You'd think that a heavy weight champion's doctor would be very careful about diagnosing something like that. He goes to a healing crusade, the condition is gone, and suddenly his previous diagnosis is said to have been false. You'd think they'd get the diagnosis right if getting it wrong meant millions.
To answer your question, yes I think unbelief is a big problem. Reading the Bible, I get the impression that there may have been more miracles in places where the Gospel is being preached for the first time. Also, unbelief in a city can prevent miracles from happening as we read about Nazareth in the Gospels.
On the other hand, there are loud preachers who make a lot of claims when there is very little evidence. Some of this is because they are trying to encourage faith. Some of these preachers are from a Word of Faith type background where they don't believe in saying anything negative and believe in saying positive things.
Some of these preachers come from a church subculture where hype is very much appreciated. This turns a lot of people off, and makes them more skeptical of healing.
And God can even heal people in meetings of people who are a bit off, and maybe seem flaky. At some of these healing crusades, people get healed hours before the preacher shows up as believers in Christ pray for them.
People say Benny Hinn is supposed to be a healing evangelist. But I've only seen one scene where he was supposed to have laid hands on someone someone who got healed, a guy with a cast in Iceland. The rest of the time, people pray and sing. Benny Hinn doesn't ask questions like, "Could you walk without the wheelchair before you got up on stage?" He asks "What did you feel go through you?" So if an air conditioning or heat vent comes on, some sick person might go up to the front because he felt a physical sensation. Some of the preachers who do these crusades don't screen the testimonies they give.
I knew one guy who had the incurable type of diabetes. He went to a Benny Hinn crusade and Benny Hinn got a word about someone in his section being healed (maybe from diabetes, memory fails) as his church friends prayed for him. The guy being prayed for fell down. He stopped taking his insulin, over the objections of these church friends of his. He was fine. He didn't have diabetes.
But then he pigged out so much he ended up getting the other type of diabetes, the borderline kind, not the incurable kind. (I mean types A and B.) I've seen this guy eat before, and I could see how that could have happened.
I don't agree with a lot of things Benny Hinn has said, but I don't think that necessarily keeps people from being healed in his meetings, especially since Christians are praying for one another for hours beforehand.
