It depends on state law. Being from Michigan and since the subject of the OP is also in Michigan I will take your word for it but in Ind for instance, if you are arrested for carrying a handgun without a license but you later show you have a valid LTCH all record of your arrest is destroyed.
It could be different for other things but that is one example I can think of.
I don't know about the legal records (although it seems the government always has a record of anything that has happened), but google certainly exists. The history is there, so the poster's question about job applications, etc. is still valid. Just like if Zimmerman is found "Not Guilty." Do you think it will be like he was never arrested and prosecuted?