A prayer is completely open communication. You shouldn't/can't censor yourself and should say exactly what you mean. Don't hide things and don't say things "because it's the right thing to say."
However, if its an "I want to win" or "I want an iPad" or "I want to go to this party" sort of thing, then yeah it could be considered misguided. Not necessarily the subject itself, but because it's being thought along an "I want" train of thought. It's a little hard to explain, but that thought process isn't... ideal. Instead it should be "help me be good so I can go to the party" or "help me perform my best on competition day." Saying or not saying "I want" isn't the issue, it's that way of thinking. You could say "help me be good" and still be thinking in a shallow "I want" phase. Does that make sense?
There have been claims and concerns about prayers being unsound and misguided at times. This is seen when we try to perform some form of religious legalistic practices before prayers. When we pray, we should pray boldly believing that whatever we ask for will be given unto us.
Absolutely! Someone once asked me to pray they got a car. They had no job, money or credit but was going to try to finance. They asked, I said yes and I don't say things I don't do. So I said "God I'm so sorry to ask this, I do know better but I promised....." THEY GOT THE CAR! I was blown away! Then they cracked it up 2 weeks later. They were ok but it shows, be very careful what you pray for, you might get it. Be thankful for what we have. God knows what we want already.
Well yeah. Being flawed humans we tend to pray for unsound things a lot. Like praying to win the lottery or praying bad things on people we dont like or asking God to let us have something bad for us like another married person.