Political advertising

Today is the midterm elections. Because of that the TV was full with political ads in the last couple of weeks. Political ads are much simpler than in Europe. Basically they follow this schema:

"My opponent is an asshole while I'm a saint, vote for me!"

The term asshole can be replaced with the following synonimes:

• voted for tax rase,
• helped killing small businesses,
• corrupt,
• wants to ban abortion,
• etc.

Ads never reveal the political goals set by the candidate. I have no idea how Americans can decide, since the other party says the very same of his/her opponent in his/her ads. So either both are assholes or both are saints. How can you make up your mind then? I think I still have a lot to learn about "democracy" ;)