I'm at my grandfather's funeral today, and literally half the people there were wearing something I thought was completely inappropriate. One dude was wearing a fucking batman T-shirt and fucking jeans. My cousin was in a full blown cowboy get up complete with jeans, flannel, cowboy hat and boots with a giant ass belt buckle. Keep in mind this kid was born and raised in northern Michigan. He hasn't rode a horse a day in his life.
Now I'm not expecting everyone to show up in a suit and tie but to me, jeans are absolutely unacceptable funeral attire.
I wear a suit and tie, it should be business casual at the very least. Anything else is disrespectful imo.