One man's mistakes are another man's treasures.
Most astronomers already know the story.
In 1758, French comet hunter Charles Messier found M1, the Crab Nebula, while following a comet. Over the next 30 years, he discovered 106 more objects and cataloged them so that other comet hunters wouldn't mistake them for comets. We now have Messier marathons, Astronomical League Messier observing clubs, and other activities associated with these Messier objects. Being 18 years old and an enthusiastic observer, I've recently completed the AL's Binocular Messier and Honorary Messier clubs and can heartily recommend them both. The Binocular Messier club requires that you observe any 50 Messier objects with any size binoculars.