Adams' campaign distributed the Coffin Handbill, a pamphlet which claimed Jackson (being a lunatic) killed six innocent soldiers in New Orleans for absolutely no reason. Now in reality Jackson was a little insane and, sure, he probably personally killed a ton of people for no reason. But in this case the soldiers were guilty of robbery, arson, mutiny and desertion. They were tried, found guilty and executed, as was the custom of the time. None of those details were considered important enough to include in the pamphlet, of course.
Still, deliberately misleading voters by ignoring details wasn't enough for the Adams side, so they resorted to cheap, schoolyard dickery. The Cincinnati Gazette was sent an "anonymous" tip (which it promptly printed) saying "General Jackson's mother was a COMMON PROSTITUTE," (capital letters theirs, not ours), and that his father was "a MULATTO MAN."
Worst of all, the Gazette broke a story about Jackson's wife, Rachel. The paper explained that Jackson and Rachel got married even though Rachel was still married to some other guy, making both of them adulterers. In reality it was just a matter of confusion over the divorce papers, but still the accusations of adultery were so hurtful to Rachel that she eventually became ill and died as a result of the stress and humiliation (so, uh...point Adams, we guess).
"I'll kill your wife, I don't even care."
Finally, in what has to be the least subtle negative ad technique in history, Adams' people distributed flyers that said, "Jackson is to be President, and you will be HANGED." It's true! Jackson is running for president on a platform of Murdering Everyone. That he even got the nomination in the first place is just a shocking oversight on everybody's part.
Jackson did win the election, but became bitter and, if possible, even more crazy than he already was as a result.