I recently heard Gavin McGrath speaking and he was asked what he thinks constitutes dangerous preaching. I really liked his list of four off the top, as it were:
1. False teaching – of course.
But in good church circles, the other three would be –
2. The mocking or patronizing of non-Christians – So easily done, so unhelpful to all.
3. Legalism and feeding religiosity – If you perform better then you will be a better Christian. This leads to either pride or despair, but neither are helpful.
4. Formulaically simple preaching – Just follow this abc and you will have better life. Problem is that the Bible doesn’t teach that, nor is it effective.
What would you add now that you’ve had time to think about it?
Biblical Preaching 
Similar to #2, I’d add “Mocking or demeaning Christians of other denominations”. Too often done to make us feel “special” or to portray our own take on things as the “authentic” one.