Living in Houston, one is constantly exposed to Joel Osteen and his "Be a good person and ask God for stuff and he will give it to you!!" brand of "Christianity". I don't believe that God doles out material wealth based on how much you ask for or because you feel like you deserve it. But it sure is a popular message. Be nice! Get money! People can wrap their minds around that.
On the one hand, it is hard to be negative about a message that tells everyone to be positive and be happy and treat everyone nicely (unless they are flight attendants, but whatever). On the other hand, promising someone something good in a material way will happen if they only have this kind of faith does nothing but turn people off when that material miracle doesn't happen.
Same with Mormons. I have heard it said before that it is hard to bash a religion that prohibits drinking and drugs and stimulants, encourages families to spend lots of time together, to live a good, clean, wholesome life, to go to church and be an example to others. That is completely true. But it's all that freaky deaky stuff that you find behind the scenes when you roll the rock over that makes this particular religion suspect.
Many Protestants may be perceived as self-righteous and hypocritical, but anyone is welcome to attend a church service simply by walking through the front door. No need for a membership card. Anyone can hear the entire belief system of the church without wearing special underwear and going through special rituals. It is the secrecy that sets Mormons and Scientologists apart from mainstream religions and causes others to be suspect of their motives and beliefs.