Oil Drops vs Fungus Inside Lens

HW Stone answered a post from Rafael Pankratau asking whether a lens had oil drops or fungus on the inside elements.

"Oil drops [look like streaks, scratches, small bubbles, and/or drops]. Cement flaws look like torn pieces of paper, fungus looks like spiders or fuzzy carpet bits."

Lens oil drops
Lens oil drops

"About one out of ten shipments, that [(leaked oil drops)] happens, no matter how well lenses are packed. [Leaked oil drops happen] most frequently during cold weather, when the lens gets very cold and squeezes the oil out of the areas it normally would be lubricating. Over nine out of ten times it cleans out easily, and you can relube the lens when you put it back together. Sometimes you just cannot get it out, usually because it wound up in a group that does not come apart."

"I would clean it AFTER I did a still shot with it to see how much effect the dots really have. In many cases they add halo effects to lights but nothing else, and cleaning them and finding the halo gone makes selling it much easier."