The description is something like "Sometimes when you kill a foe it explodes in a shower of caps." What does that mean? Will there be loose caps lying all around the body? Will there significantly more caps found on the corpse? Or do the caps magically appear in your Inventory?

Here's a link to the Wiki page refering to the Cap Collector Perk. Hope it helps.

http://fallout.wikia.com/wiki/Cap_Collector

It's the same as a the bottlecap mine. pile of caps treated as a single object worth 18-22 caps.