The description of the process above is for cameras/shutters with tell-tale signs of fungus... The "sniff test" is good, as your nose is a sensitive instrument, so if it is a little musty smelling, at least bag/fume the camera for at least 2-3 days, so the "colony" does not activate and contaminate your cases or gear locker if infected...

I briefly lived in Gulf Coast rural Florida (where mold/mildew was an issue), and would sometimes open up a case that was stored in an outdoor shed, and there might be one of my cameras covered with an 0.5mm layer of bright lime green mold that looked like it would glow in the dark if exposed to a bright light briefly... Most would just throw it away, but I have restored several that even I can't tell there was a huge mess on them now (and still use)...

Some that I know have bought online gear from the SE USA, that reeked, made you sneeze, and bothered your eyes when opening the package, and I think these had to be treated before bringing inside the home... Sniff test everything you buy, as I have been on studio shoots where someone would bring in gear or props that were infected, and less than hours later, the air in the large room had this stuff floating around in it, causing irritation, could make you ill, and can't be good for stuff in the space... Note that some soggy places have more than usual levels of heat/mold/mildew, and some hot/dry places less, so consider where your purchase will come from...

As a tech/restorer, I have a policy (for myself) called a "critter check", which means that ANY item (photo/antique/electronic etc) that I bring home gets a through (about 10 min.) inspection before I bring it inside... What else lives inside the item I will be working on??? Photo stuff not usually a culprit in there that can't be found with a "sniff test", but wooden items are carefully checked for maybe a small pile of sawdust near a tiny hole inside the back, maybe black widow spiders, rough/sharp edges that can cut me when I grab it, all electronic gear gets it's covers pulled off for a peek inside (I do this from when I was an audio tech in NYC long ago, and someone asked me to see what was wrong with a stereo receiver, checking on the bench I was inspecting the outsides for obvious issues, and when turning the tuning dial I noticed that that the station pointer was moving "backwards" as I turned back and forth, but a closer look was that a roach was inside running away from the pointer, so I brought it outside (on the NYC street) and removed the cover, when about 70ish roaches all escaped at the same time from inside...) and look for signs of life, loose parts etc... I do this in daylight, and shoot it with a digicam for a record before starting...

Steve T is right about fungus + glass, but I'll add that most post-war lenses are coated (and where elements containing fluorite are common), so if you see some coating issue, there's probably a trace of fungus under it causing it, and usually pitting of the glass, but as mentioned, sometimes it still can be used...

There are more aggressive methods involving thymol for cleaning, but the above is usually fine for normal cleaning (and less toxic for you), and generally safe for gear...

Steve K