I know moths can eat sweaters and blankets and even your food, but are all of them damaging like that or are there friendly moths I shouldn't worry about?

Meal MothThe pupal form of this pest can destroy any stored grain product. Usually, the infestation of a home is started by bringing in infected grains. More rarely, the female moth lays eggs inside the grains at a rate of hundreds per female. It is rather difficult to distinguish the meal moths from other moths. The best deterrent is to seal dry foodstuff in plastic or metal containers after a thorough freezing.

Clothes MothAdult moths do not feed - it is the moth larvae that attack fabrics. One way to distinguish between other moths and the clothes moth is by using light. Clothes moths do not fly towards light like others do. Clothes moths are usually smaller that other moths, being 1/4" long with a wingspan of 1/2", and the larvae are approximately 3/8" long.

Moth

Clothes moths and grain moths are frequently found in homes because they find food and shelter there. There are many other moths that are occasional invaders. Most of these wander in, attracted to lights, and can't get back out. They are unlikely to harm anything, but can be annoying.

Brown MothColorful Moth