MCE 85 (like its predecessor MCE 86) has a very high sensitivity in comparison to most other microphones. Therefore, it can pick up sounds from quieter or farther sources - all ambient noise (flattering of leaves, street noise, etc.) also gets picked up with higher level (a microphone on its own cannot separate between wanted and unwanted sounds!). So, MCE 85 records everything "louder" than most other microphones: the signal you want - but also noise.
The benefit of this approach is, that you often need less (eventually noisy) gain from your recorder or your camera.