I shall attempt to answer your question:
The reason you don't get instructions with exploits is that you don't need them.
The general function of an exploit is to gain unauthorised access, so it is just like having the administrator's ID and password, and you don't need instructions for those
All you have to do is run the exploit against a vulnerable machine. And then know what to do afterwards
You seem to be getting a little confused with trojans, password sniffers, keyloggers and the like. These are TOOLS so they have instructions.
Come to think of it, I can't recall having seen a virus with an instruction manual either
They are just not that sort of software?
