My worst crawlspace experience was in a brand-new house that my family bought in 1972. I was only 11 at the time and had no clue what to expect in there. We had no hot water and the plumbing contractor came over to see what was wrong. Being eager, I volunteered to go into the crawlspace since the plumber was somewhat hesitant to enter. He just wanted me to verify that the water heater was actually connected.
I went barreling in there to find that the cable had never been connected to the WH. On my way out on my hands and knees, I managed to encounter several large shavings of sheet metal from the HVAC installers. There was a field of scraps that were just barely beneath the soil.
This resulted in a trip to the emergency room: Three stitches in one knee, five in the other and and two deep slits in my left hand/wrist later, I learned to be more careful in crawlspaces. Hey, it was dark in there and long before there was a requirement for lighting in such areas.
Despite the fact that I was bleeding like a stuck pig, there was a small snake in there that I couldn't resist. If memory serves me correctly, I also had a frog in my pocket. While my bleeding was the least of my worries, I caught the snake and brought him out with me. I and asked my mom if I could keep him as a pet. Turns out that he was a copperhead and could have/should have bitten me, but he didn't. Mom still said no.
This was in North Carolina, where crawlspaces are full of black widow spiders and snakes. Not knowing any better, I used that crawlspace as my "fort" for two years. Now that I look back at it, I guess I'm lucky to be alive.