Formality - We are creatures of habit and routine. We all tend to have our own phrases and manner of approach to the Lord. It is therefore easy for prayer to become so predictable. Interestingly, John Newton used this observation as an argument in favour of the use of written prayers in public worship. In most extemporaneous prayers, he maintained, you recognised the beginning, could discern the middle and you knew when it was coming to an end, so why not use written ones, was his conclusion. The problem of excessive length and formality was dealt with very succinctly by D. L. Moody when he said: 'Some people's prayers need to be cut off at both ends and set on fire in the middle.'
Vagueness or being unspecific - Although prayer involves communion with the Lord and a worshipping frame of mind yet we are to make requests. The story is told of a prayer meeting where one brother seemed to be preaching rather than praying. One sister felt especially troubled by this, so she interrupted by calling out: 'Ask for something!'
Prayers that are unduly personal - very little prayer or desire may be expressed for the conversion of sinners and the furtherance of the gospel: instead, the time is spent in an introspective rehearsing of numerous personal doubts and fears. One preacher described it as 'hanging out the dirty washing for all to see'.
Pride - a desire to be seen and heard. The heart being uplifted at the thought of an opportunity to show others one's 'gift in prayer'. This was the downfall of the Pharisees: they wished to be seen of men. To quote the theologian, Robert Reymond: 'When you pray, remember whose attention you wish to gain.’
To quote Spurgeon again: 'It is necessary to draw near unto God, but it is not required of you to prolong your speech till everyone is longing to hear the word “Amen”'. The only exception I believe is if a spirit of prayer and supplication is poured out upon one member in a special way. They will know, and every spiritually-minded person will know, and will lose sight of the time.
(Taken from our church's bulletin meditation, emphasis mine)