Don't forget to up-vote the question or answer if you find it helpful! If it's your own question and you're very happy with an answer you can accept it as best answer.
When sticking your microphone in a pipe, always check these things:
1) What's in the pipe?
2) What's going to be coming and going in the pipe?
3) Always have a softie or something on it to be safe.
During SFX gathering on top of a skyscraper, there was a nice looking pipe that had some cool echo and a regular beeping that I could hear when I put my mic down there. There was also a funky smell and some water sloshing sounds. When I took my mic out, my dead cat looked like a side of it had been licked like actual cat fur looking licked--matted and wet. Always use a softie!
Mic was unscathed.
It turns out that the machines on the roof near the pipe were sewage treatment/water treatment for the building and that also explained the smell coming from the pipe.
I think my answer will have to be "use common sense".
It's a skill acquired where you know what will happen if you do "so and so".
Meaning: You can sort of predict that your microphone will get soaked if you drop it in water.
I personally never let my mikes get exposed to extreme wind even if the manufacturer says they can be. I also make sure I turn off phantom power or the pre if I can't otherwise turn it off before I plug in or unplug my mic. I also make sure to place my mikes in their boxes or safe compartments or cabinets at night and I never leave them out on a stand overnight or for long periods of time in the studio. This is something I've learned from Bruce Swedien and I used to scoff at people who told me to do these types of things before I held his mint condition U-47 he bought 20+ years go.. It looks brand new. And the quality of sound from mikes I've found to be directly proportionate to their care.
Throw up a brand new MK41 against a used rental model that's been beat up and that will dispel any facts to the contrary, I think.
Please note: When commenting on someone's question or answer, you will not receive notification on follow up comments unless you are mentioned with @Username. So for Andrew Spitz, you only need to use @Andrew