Setting things on fire

The rules for setting things on fire say clothing / hair / equipment. What if the creature doesnt have clothing or hair or equipment? Lets say a skeleton walks through a burning patch of fire. They take d6 damage but am guessing no chance of catching on fire if there isnt any clothing. If they are wearing tattered rags, maybe 1 round of fire before they are burnt away.

My players ask because they have some dragonsbreath arrows which it says have a chance of setting something on fire, but dont mention clothing / hair. I'm pretty sure that it should be ruled the same way, unless there is something flammable, that wont work.

So, now they are thinking to throw flasks of oil at the current enemy and then fire the dragonsbreath arrows at it. That sounds like it could work, though not sure how long the burning oil would do damage for.

That depends on how much oil is involved. Under the presentation of lantern oil, it tells you how long a given quantity can burn.

Most enemies will probably want to put the fire out first.