I'm not going to share all my kitchen appliances with my roommates.
Why wouldn't you  share your kitchen appliances?
I'm concerned there could be germs on it and make them sick.
It's reasonable to want to protect your kitchen appliances, but it's also nice to share appliances with your roommates. If you're concerned that your roommates may get sick from using your appliances, then be sure to thoroughly clean them. If you share your appliances with your roommates, they'll be grateful to you and you would seem kinder.
They won't properly wash them either, and are you insinuating that I'm selfish?
They're your roommates after all, so it makes sense to share. You can always set boundaries on how to take care of the appliances, and I'm sorry if I came off that ways.