I know no one (excluding the nuts on TV) who ever say "they" heal anyone. I do, however, know several people who come right out and tell people that God wants to heal them. I don't go that way, and I still am not sure why they do, despite the fact that the "healings" I have seen them help bring do seem to always work.
Personally, I feel that we should respond when we experience that tugging to "go to that person", whether they 'get healed', or not. I believe, for a fact, that there are any number of internal impressions and responses God may have in mind for the recipient when we do as He asks, and go tell the person that we feel God wants us to pray for their situation, and would it be alright with them if we did so.
Even if it may be no more than for them to see that we just accept their scalding rejection when we ask, I believe that might just be the specific thing God may be wanting them to see... both about themselves, and about our unflustered reaction to their anger and irritation.
At some of those times when nothing much happened, I have often seen people express such appreciation that I (or sometimes, we) noticed them and their pain, and cared enough to at least "try" to help them with prayer.
I think we all (us believers in this stuff, and you other guys, too) have a tendency to KNOW what's what in God's world, and how things are "supposed" to work..... and if things don't go down according to our limited understanding, we assume the encounter was a failure. This may not be true, at all. After all if we did not have the Bible to tell us differently, we would be forced to say that we would have to admit we view Jesus' entire ministry as an abject failure.... after all, He got himself killed within three short years, and never made a dime out of it.