Can prayers be InValid?

October 5, 2006: It's about 8 am, and while I was getting ready to leave for office, my Mom's hooked on to the telly, 'cos God TV is showing a miracle crusade and the pastor started praying for the viewers and the audience present for the show. As he prayed, he moved people emotionally, spiritually (depends), took a few names saying they're being healed... and he closed the prayer with words of affirmation.

While just walking around my home looking for my shoes, tie, etc., I saw an announcement at end of the show. "Sep 29 is a special day of prayer, and I urge you to send in your prayer requests." Bingo! Did that strike you? Broadcasted on the 5th of October, recorded - I don't know when, but a day before Sep 29 for sure...

Few months back, when MiracleNet was available on our cable network, I saw another pastor (no names), based out of Mumbai, who believed in pronouncing the name of Jesus as many times (like a mantra), he went to extent of even creating a gadget (something like a calling bell), so that you switch it on, and the name of Jesus is heard on and on and on... (in the pastor's voice)... And many as the people in the program said, they bought it... because they believe it. Is that prayer??? Is that permissible at all???

The issue that bothers me is: Can Prayers be Invalid???

We see a lot of miracle crusades that happen, and if not such crusades, revival meetings etc., that are broadcasted even after years and decades (e.g., Rev. Billy Graham's crusades). While I do understand and agree to unite with someone in prayer, for salvation, for revival, for personal growth, for any good cause... I don't understand how uniting in a recorded prayer that named somone (to have been healed then) days ago or months ago, who knows, even years... helps me, or the other ones spiritually.

I would also want to demarcate here the purposes of prayer:
-- A prayer for salvation, probably, that perhaps can be repeated as a new person unites in the prayer.
-- Special prayers - can't be repeated, 'cos they're for a specific purpose...
-- Healing prayers - All doubts, but when names are mentioned for that moment... how can they be repeated???

Given that these prayers create an inclination to positivity, they also give an emotional high (whether or not spiritual is personal), do they serve the right purpose?

There might be (not sure) a doctinal issue in this too. 'Repeated Words,' cannot be what we desire that should be, but then, is it only applicable to miracle & healing prayers or even daily sermons and other preachings?

Towards the end of it, I do understand that, everything boils down a personal level, my motives and what I believe(My defence is of God, which saveth the upright in heart), and if I have the faith nothing is impossible (with God all things are possible)... but through such prayers and practices, are we deceiving ourselves? What do we do?