What’s the motive? If these evangelicals get money out of it...then I would doubt their sincerity.Which "words" of Christ are the true ones? JW's? Mormons? Catholics? Pentecostals? Fundamentalists? Only a couple of the Christian groups bother to go out and knock on people's doors. Only a couple of them think that the Word is important enough to take it right to the people. Some people in some of the other sects get up on their soapboxes and shout at the people around them to repent that the day of the Lord is near. But, how many people are just plain old annoyed with this?
So you believe your group has the truth. And, it exhorts its people to go out and evangelize. Then what do you think of other "Christian" groups, whose teachings are a little off? Are their purposes nefarious? Are they just blind follower and don't realize they are being deceived? Do they believe your group is the one that is wrong and do have a nefarious plot to spread lies? Do some Christian groups do warn their congregation to avoid certain other religious groups so as not to get "infected"? Infected with false teachings? Probably, and they should, 'cause people will get affected by what others say and might just change their beliefs and agree with the other group.
I would imagine that most TV evangelists have some nefarious scheme going on... Especially the spiritual healings and "prosperity gospel" preachers. So we gotta avoid and be wary of some of them. So can we and should we trust the people coming to our door with pamphlets in their hands? Since it is pretty much just two Christian groups that go to people's houses, should we trust the one and not the other? But... I'm not just talking about Christians. There is another religious group that does the "subtle" more "sneaky" way of proselytizing. As do some of these other Christian groups. Naturally, they justify it, because they think they have the truth. But what else can they do? To make "friends" with people first seems innocent enough. But, if the real purpose is to "teach" the new "friend" about their religion, is that nefarious? They don't come cold calling, they find ways to get unwary people to open the door and let them right on in.
Of course, money doesn’t have to be the motive....there are others....but money is the most obvious.