I'm out of my depth here. (The last time I did any form of decorating was when I moved into this house 30 years ago). However a web search shows that it's perfectly possible to paint over tiles (including in steamy locations, such as bathrooms and kitchens) as long as you use specialist tile paint, such as that made by Ronseal.
Not something I would recommend as it will probably only last a short time. If you do paint them then you need to make sure you prepare them really well as if there is any grease or dirt on any part of them it will start to come away. It can look quite good if it is done correctly but water and steam will have an effect on it and it may chip if you catch it with something. They can be tiled over if that is an option.