I won't make the claim that all big, big churches are bad but what percentage would you say that are bad? Pretty high if we're comparing them to churches that are biblically rooted. In my opinion the postmodern mindset of many big, big church leaders is that church growth is more important that staying biblically sound. The message have been softened not to offend, quotes from the bible lessened to keep people awake and more giant screen TV previews of contemporary movies for the newbies to relate to. And really all they are saying with these actions is the Word of God is not good enough for people today so we have to jazz it up, add to it. The farther we move from the Word of God and dumb down the message the more we embrace weak teaching.
Below is a video I found that asks the modern church goer to ponder what we consider church to be today. How did Paul ever manage without giant TV screens and million dollar sound systems?