There are so many false teachers out there preaching their own doctrine. Each have a tremendous following. The only way to know if you are hearing 'Truth' or not, is to know enough of the word of God for yourself.
Everything I hear, I look to see where it lines up with the word of God. There's a lot of messages being preached that cater to the emotions. Some preaching sounds so good, you'd automatically think it was authentic in its truth, but it's an imposter.
How well do you know your bible? What is it that you want to hear preached? Today, you hardly hear preachers on Television talk about 'Sin', and that's a serious problem right there. They talk about everything else except for the lifestyle a true believer is to have. You hear those 'Feel Good' messages, the ones that go down easy without a challenge to rise to a higher level of accountability.
Don't neglect reading and studying your bible. This is imperative! There's so many voices out there speaking all sorts of things. Question any preaching from individuals who have aligned themselves comfortably with unbelievers. The word of God clearly states that since the world hated Christ, they will automatically hate His followers. How could a believer be accepted in the company of unregenerate men and partner with them in their endeavors?
Don't be deceived! Always check what you hear against the written word of God! Don't be fooled!