Information on co-signers?

Basically If you don't make a payments and then it goes to collections or your car gets taken away it is your co signers responsibility to pay off that debt and yes you will mess up there credit. But if you can pay your payments on time and get it paid off YOU still earn credit because you paid for the car!! I could never co sign for someone unless i knew with out a shawdow of a doubt they are responsible people.