I know exactly what you mean as my DH has also had a stroke and sometimes their filter goes. Would he mind wearing a Lanyard, with either the stroke association of the Sunflower emblem on for hidden disabilities, they were being giving the free in some supermarkets or you can buy them from Amazon, does he mind you correcting him gently? Mine does sometimes . Don't forget the stroke has killed some of the brain cells and it can stop them remembering not to say something, or being overly friendly , we know someone like this who comes out with some near the knuckle lines , sometimes my DH comes across as being disinterested when people are saying something. I sometimes give him a gentle reminder before we go somewhere about making sure he listens and engages his brain. But I know it can be hard for them.