Is crop dusting good or bad why?

It depends on your perspective. With any technological agricultural practice, there are both risks and benefits. Generally, the benefits outweigh the risks or else no one would be doing them.

With crop dusters, or ag. aircraft, one risk can be the potential for wind-borne drift of a hazardous material such as a pesticide or fertilizer. Another risk is the low-flying nature of the activity. These aircraft do occasionally crash, sometimes taking the life of its pilot. Is it worth it? Most of these pilots will respond with an enthusiastic "Yes!" because of their love for the job.