The answer to 'spider odor' is that a strong, unpleasant odor coming from spiders is usually caused by a buildup of their pheromones or the release of defensive chemicals. This can happen when there is a large spider infestation in the home, or if spiders are being crushed or disturbed.
The odor is often described as a musty, sour, or even ammonia-like smell. It's not harmful to humans, but it can be very unpleasant and indicate a larger pest problem that needs to be addressed. In most cases, the best solution is to eliminate the spider infestation through proper pest control methods, either by doing it yourself or calling in a professional exterminator.