what is the most effective method for detecting mold and spores?
It’s like real estate–it depends on location, location, location.
So the answer is: it depends.
The most obvious method and the most likely answer is sampling. Take the sample, send to the lab. (etc) But if you can’t see it, if mold is behind the walls, you don’t want to go ripping up walls just to see if something might be there.
ByebyeMold has the most up-to-date tools available that can detect conditions behind walls and particulates in the air. Technology is wonderful.