While there isn't a definitive "enemy" of a microscope, here are two common challenges that can severely impact its performance:

1. Contamination: Dust, dirt, fingerprints, and even airborne particles can accumulate on the lenses and other delicate parts of the microscope. This contamination can scatter light, obstruct the image, and even scratch the delicate lenses.

2. Vibration: Microscopes are extremely sensitive instruments. Even slight vibrations, whether from foot traffic, nearby machinery, or even a slight bump, can blur the image and make it difficult to focus.

These challenges are not inherent "enemies" in the traditional sense, but they can be major obstacles to clear and accurate viewing under a microscope.