Filament, or rather, improper use and storage of filament, can cause a lot of issues. 

Most of it is porous. What this means is that it will absorb moisture over time, especially in humid areas. If you do end up using wet filament, you might notice a couple of things. It might pop or bubble as it is extruded as the moisture boils. It might extrude with holes in the filament for the same reason. Almost certainly, your printed part will have a very poor surface finish.

To remedy this, store filament in a dry area and, as an extra measure, dehydrate it before use.