I don't pretend to watch these shows to try to figure out the crime before the detective does. It is just entertainment. But the entertainment only works because the process works - unless the writer can provide enough rational steps to the conclusion, the viewer will feel cheated.
Basically, as Grissom keeps saying, it's all about evidence. These shows all have the same formula, but there is infinite variety. There is always something incredible, something that defies explanation, something that might have been caused by some supernatural freak occurrence. But there was none.
There is always a logical explanation. Yes the final explanation can be complicated and tortuous and involve the strangest aspects of our fleshy bodies and animal desires. But ultimately the answers are all in there.