Snot is running down his nose, greasy fingers, smearing shabby clothes.
When biblical material touches on the natural world, we can legitimately use the tools of science. Sometimes that shows us - no shock here - that biblical writers didn't know as much as we now know about the natural world - but God knew that when he picked them, so that alone tells us that "doing science" that would satisfy a 21st century - and beyond - audience wasn't what God was interested in with respect to the enterprise of producing Scripture for posterity.