Fertile bearded dragon eggs look plump and bright white in color; infertile or otherwise compromised eggs look yellowish, and they are usually misshapen or deflated. It does not hurt to place presumably infertile eggs in an incubator for a few days before discarding them, as a small percentage may prove to be fertile and viable. Many clutches contain a few infertile eggs, which is normal and not indicative of serious health problems.
To be 100 percent sure bearded dragon eggs are not fertile, “candle” the eggs before removing them from the incubator. To candle eggs, bring them into a dark room and hold a small LED flashlight against the side of each one. Starting about three days after egg deposition, a small, red circle of tiny blood vessel should be visible in fertile eggs. A few days later, more blood vessels will have developed, causing the eggs to glow uniformly red or pink. When you shine a light through an infertile egg, it will appear uniformly yellow. Unless the eggs are moldy or decomposing, you can simply continue incubating them to err on the safe side.