I started putting hats on my boa about two years ago, and she now has a couple thousand followers, many of which are not snake people. It's actually been really positive because it's gotten a lot of people who previously hated snakes to reconsider. I really think that when done carefully it can be a huge way to reach out and educate people. She has changed many many minds.
I either just set them on her head carefully, or else use a tiny bit of peanut butter. I see no reason why it would be an issue. I clean it off gently as soon as I'm done taking pictures. Figment is a very tolerant snake.
Here are a few of my favorites.
And the one that started it all...
The one with the birthday hat is the one I've been showing my friends when they think I'm crazy wanting to know how to make snake hats. I found it on Google images, nice to meet the person who did it!