One time I was in a building where they had a vaulted ceiling but there was still a small attic space above the ceiling. It was so tight that I was crawling on my stomach with my shoulders very snug on either side, not a good feeling. Then they started tearing off the front porch with heavy machinery! Only the front porch was scheduled to be destroyed and I was far from it but being in a tight space and feeling even part of the house being torn down is enough to want out! Got a ton of insulation out of it before they tore the whole thing down though
Then there was the time in the old house where the crawl was covered in some kind of mold on the ground AND heavily invest with these things:
I felt like I was in some kind of alien movie crawling around in a mushroom forest with giant spiders all around me. They had a huge moisture problem and those spiders love moisture (so did the mold!).