Laser Spy microphone

it does work, thats what the government did back in the day to listen in onto conversations inside of the Russian Embassy in Washington D.C.

yeah might not always work;
you are skipping over

Dual paned windows
Windows that are made of bulletproof material
What if you are unable to position the equipment in a way so that the beam bounces to a place that you can also get to? For example- how would you listen to a conversation happening on a 2nd floor window from the ground floor?
I have a feeling that this only works at night
What if the people talk in a bathroom, or a place without windows?
Won't they see the laser pointer dot on one of the walls in their house?
Laser pointers run out of battery *really* quickly when held continuously on(and those batteries are hard to find)
The list goes on