Yes they can. But there are all methods and types of paint and materials that are required. What exactly are you thinking of to paint? Counters, walls, floors? All have different answers and methods. So tell us a bit more so we can focus more on your question.
I am going to be using them for a back splash around my stove
Yes you can paint them, but remember the quality of the finish will not be as durable as you may want. With grease splashing and needing to scrub a bit on occasion to clean, the finish may not last quite as long as you may like. However there are several high quality counter paints that are gaining popularity and will work fine for what your looking to do.
Do a search in the bubble at the top. Put in paint Countertops. There is a ton of valuable information you can read.
Can you help me with bathroom floor and shower area painting?