I'm surprised how many times I've heard that.
I have lots of friends who aren't Mormon, but few ask me questions about it. They get their information (and misinformation) about Mormons from somewhere else. But not just information, they get their attitude toward Mormons from others -- which seems to include a lot of distrust, and more skepticism.
What do people think Mormons believe anyway? That we all get lots of wives and are quietly prejudiced and think Adam is god and god was once a regular guy and we kill sinners and that people live on the moon? I think those are the worst of the ones that I at least know where they came from. In high school and college, kids told me that we worship Joseph Smith, that an apostle has to sleep with every woman who goes in the temple, that we don't believe the Bible, and that Mormons have horns (and lots of other things).
Well, all of those are flat wrong. And we don't believe any of them.
In the early days of the church they didn't have tape recorders or video cameras. Their speeches were written down by whoever happened to be there. Most of those statements in the first list above were written by folks listening to Pres. Smith in the 1840s and Pres. Young in the 1850s-80s. And all of those statements been downplayed by subsequent prophets as inaccurate, or at least incomplete.
I happen to think they were misunderstood or mistranscribed by the writers.
And guess what: not everything that every modern prophet or apostle says or writes is considered church "doctrine" (or "official teachings"). We are only required to believe things that are in the scriptures, that are told to us by the prophet (President of the Church), or that the Holy Ghost has put in our hearts and we *know* to be true. That's why I don't believe any of those things that I listed above.
So what do Mormons believe? Joseph Smith himself answered this question in 1842 in a letter to "Long" John Wentworth who was the editor of the Chicago Democrat. His response is now referred to as the Articles of Faith. So here's a challenge for you: write down the first 3 Mormon beliefs that come to your mind. Then, go see if you can find them in the Articles of Faith.
Let me know how you did. =)