While firm and heavy bulbs suggest they are in decent condition (at least currently), we can't say with certainty that they are or are not carrying a pest or pathogen based on their appearance. If you are skeptical of their health, it would be safest not to plant them, especially for the sake of bulbs growing near where they would be planted. Nematodes would be hard to detect without a lab or microscope (though tend to be associated with soft bulb tissues, which sounds like these don't have) and bulb mites would similarly be not readily visible as a means of confirming a diagnosis. If you want to experiment and aren't sure you want to discard them yet, you might be able to try growing them in a container, though winter hardiness is always more risky when keeping perennial plants above-ground since the roots are less insulated from temperature fluctuations.

Miri