The grossest thing a fermentation enthusiast has to go through might be insects in their jars. When a jar is not covered well, insects get attracted to it and they will lay eggs, which can hatch into maggots, on the surface. Seeing crawling things in your food is enough to creep anyone out, but if you can remove the surface layer until you reach the clean veggies or fruits, then you might be able to salvage the foods. However, if you are not feeling comfortable with that, then you are free to discard the whole jar. Preventing this situation is very easy and all you have to do is simply cover the jar properly. You can use a clean piece of cloth and secure it with a rubber band to keep any insects out. A jar that can be sealed tightly or airlocked works even better.