When Jesus preached the sermon on the mount, I don't remember him telling them to all go home and change clothes. But I do remember how he addressed the Pharisee's and their legalism. it wasn't pretty.
Should people show up to worship looking like they just rolled out the bed ? No. Unless that's all they know. Should we have a reverent posture when going to worship ? Of course. I don't understand why people shop at Wal - Mart in their pajamas, but I've not seen that at church. Yet.
More than that they are going to be shocked at some of the people who make it into heaven and even more shocked at some that don't.