After years of doing this I don't care about "seeing" the roots other then at transplant.....I still when transplanting "smell" the roots as I can tell a lot about how their doing by the smell of the media around the root ball and the exposed roots them selves....any other odor other then nice "earthy humus" smell indicates a problem somewhere....."gassy" smells indicate some type of rot in something and grainy or alcohol smells mean fermentation - most likely anaerobic involved......Ammonia or spicy smells mean someone didn't cook the soil long enough and should have smelled that before using it, because the amendments are still being broken down !
Just something I picked up a cpl a decades ago...lol
Doc