Want to know my list of cades I generally don't like people cading?

Using the shelf in Snoopie
Barricading the Red Room
The first floor of the Blue Building on 4corners (When I first thought of it I didn't realize how rigged it actually was.. So I don't use the cade anymore, and I ask other people not to as well.)
Glitching doors by mass pressing E (Note, glitched spots in walls I can get into on my first try every time.. So anyone in those are pretty much screwed when I'm on.)
Barricading vents on Holdout Mountain

There are probably more, but those are the main ones.

Anything else that people usually call "impossible" take a good 30 seconds to set up for me.. And if you're skilled enough to set up a cade properly, then you deserve to live.

The reason he probably said not to cade under the elevator in that one map is because there is a small place in the corner where you can go (behind cardboard) and the zombies can't get you.. Ever..