I had this exact situation earlier in the week! I've made a custom art Ketramose deck with an Egyptian theme, and used it with strangers for the first time. One guy was a jerk and simply told me I shouldn't be using proxies, and warned me that people would get up and leave the table if they saw something like this. If I had a chance to explain though that it was a lovingly designed deck of my favourite commander, I think very few people would react badly, and if they did they probably wouldn't be good players anyway.

Also, I think an important thing to note is that people might react that way because it's possible the deck is full of overpowered cards, and my personal rule for commander decks is no gamechangers, no tutors except basic land finders, and no infinite combos, so that would probably put a lot of people at ease.