Laser Microphone

What is your idea about this:
https://www.gearlive.com/index.php/news/article/diy_laser_microphone_05131215/

It's a well known spying device - although that does look rather crude?, but I expect at short ranges it will probably be OK?.

An obvious draw back of a visible laser is that it can be seen though!.

I hope you know they dont work with double glazing.

Andy